Add a new {% render %} tag

Example:

```
// the_count.liquid
{{ number }}! Ah ah ah.

// my_template.liquid
{% for number in range (1..3) %}
  {% render "the_count", number: number %}
{% endfor %}

Output:
1! Ah ah ah.
2! Ah ah ah.
3! Ah ah ah.
```

The `render` tag is a more strict version of the `include` tag. It is
designed to isolate itself from the parent rendering context both by
creating a new scope (which does not inherit the parent scope) and by
only inheriting "static" registers.

Static registers are those that do not hold mutable state which could
affect rendering. This again helps `render`ed templates remain entirely
separate from their calling context.

Unlike `include`, `render` does not permit specifying the target
template using a variable, only a string literal. For example, this
means that `{% render my_dynamic_template %}` is invalid syntax. This
will make it possible to statically analyze the dependencies between
templates without making Turing angry.

Note that the `static_environment` of a rendered template is inherited, unlike
the scope and regular environment. This environment is immutable from within the
template.

An alternate syntax, which mimics the `{% include ... for %}` tag is
currently in design discussion.

.github/probots.yml

@@ -0,0 +1,2 @@
+enabled:
+  - cla

.gitignore

@@ -7,3 +7,4 @@ pkg
 .ruby-version
 Gemfile.lock
 .bundle
+.byebug_history

.rubocop.yml

@@ -1,14 +1,20 @@
-inherit_from: ./.rubocop_todo.yml
+inherit_from:
+  - .rubocop_todo.yml
+  - ./.rubocop_todo.yml
+
+require: rubocop-performance
+
+Performance:
+  Enabled: true
 
 AllCops:
   Exclude:
     - 'performance/shopify/*'
+    - 'vendor/bundle/**/*'
     - 'pkg/**'
 
 Metrics/BlockNesting:
   Max: 3
-  Exclude:
-    - 'lib/liquid/block_body.rb'
 
 Metrics/ModuleLength:
   Enabled: false
@@ -31,8 +37,8 @@ Lint/ParenthesesAsGroupedExpression:
 Lint/UnusedBlockArgument:
   Enabled: false
 
-Lint/EndAlignment:
-  AlignWith: variable
+Layout/EndAlignment:
+  EnforcedStyleAlignWith: variable
 
 Lint/UnusedMethodArgument:
   Enabled: false
@@ -61,10 +67,10 @@ Style/BracesAroundHashParameters:
 Style/NumericLiterals:
   Enabled: false
 
-Style/SpaceInsideBrackets:
+Layout/SpaceInsideArrayLiteralBrackets:
   Enabled: false
 
-Style/SpaceBeforeBlockBraces:
+Layout/SpaceBeforeBlockBraces:
   Enabled: false
 
 Style/Documentation:
@@ -73,19 +79,19 @@ Style/Documentation:
 Style/ClassAndModuleChildren:
   Enabled: false
 
-Style/TrailingComma:
+Style/TrailingCommaInArrayLiteral:
   Enabled: false
 
-Style/IndentHash:
-  EnforcedStyle: consistent
+Style/TrailingCommaInHashLiteral:
+  Enabled: false
 
 Style/FormatString:
   Enabled: false
 
-Style/AlignParameters:
+Layout/AlignParameters:
   EnforcedStyle: with_fixed_indentation
 
-Style/MultilineOperationIndentation:
+Layout/MultilineOperationIndentation:
   EnforcedStyle: indented
 
 Style/IfUnlessModifier:
@@ -94,7 +100,7 @@ Style/IfUnlessModifier:
 Style/RaiseArgs:
   Enabled: false
 
-Style/DeprecatedHashMethods:
+Style/PreferredHashMethods:
   Enabled: false
 
 Style/RegexpLiteral:
@@ -103,13 +109,10 @@ Style/RegexpLiteral:
 Style/SymbolLiteral:
   Enabled: false
 
-Performance/Count:
+Naming/ConstantName:
   Enabled: false
 
-Style/ConstantName:
-  Enabled: false
-
-Style/CaseIndentation:
+Layout/CaseIndentation:
   Enabled: false
 
 Style/ClassVars:
@@ -123,3 +126,7 @@ Style/TrivialAccessors:
 
 Style/WordArray:
   Enabled: false
+
+Naming/MethodName:
+  Exclude:
+    - 'example/server/liquid_servlet.rb'

.rubocop_todo.yml

@@ -1,72 +1,345 @@
-# This configuration was generated by `rubocop --auto-gen-config`
-# on 2015-06-08 18:16:16 +0000 using RuboCop version 0.32.0.
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2019-08-29 00:43:36 +1000 using RuboCop version 0.74.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 5
-Lint/NestedMethodDefinition:
-  Enabled: false
-
-# Offense count: 53
-Metrics/AbcSize:
-  Max: 58
-
-# Offense count: 12
-Metrics/CyclomaticComplexity:
-  Max: 15
-
-# Offense count: 553
-# Configuration parameters: AllowURI, URISchemes.
-Metrics/LineLength:
-  Max: 294
-
-# Offense count: 77
-# Configuration parameters: CountComments.
-Metrics/MethodLength:
-  Max: 46
-
-# Offense count: 6
-Metrics/PerceivedComplexity:
-  Max: 13
-
-# Offense count: 1
-Style/AccessorMethodName:
-  Enabled: false
-
 # Offense count: 1
 # Cop supports --auto-correct.
-Style/ClosingParenthesisIndentation:
-  Enabled: false
-
-# Offense count: 3
-# Configuration parameters: MinBodyLength.
-Style/GuardClause:
-  Enabled: false
-
-# Offense count: 4
-# Configuration parameters: EnforcedStyle, SupportedStyles.
-Style/MethodName:
-  Enabled: false
+# Configuration parameters: TreatCommentsAsGroupSeparators, Include.
+# Include: **/*.gemspec
+Gemspec/OrderedDependencies:
+  Exclude:
+    - 'liquid.gemspec'
 
 # Offense count: 1
-Style/MultilineBlockChain:
-  Enabled: false
+# Configuration parameters: Include.
+# Include: **/*.gemspec, 
+Gemspec/RequiredRubyVersion:
+  Exclude:
+    - 'liquid.gemspec'
 
-# Offense count: 2
-# Configuration parameters: EnforcedStyle, MinBodyLength, SupportedStyles.
-Style/Next:
+# Offense count: 124
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, IndentationWidth.
+# SupportedStyles: with_first_argument, with_fixed_indentation
+Layout/AlignArguments:
   Enabled: false
 
 # Offense count: 7
 # Cop supports --auto-correct.
-# Configuration parameters: AllowAsExpressionSeparator.
-Style/Semicolon:
+# Configuration parameters: AllowMultipleStyles, EnforcedHashRocketStyle, EnforcedColonStyle, EnforcedLastArgumentHashStyle.
+# SupportedHashRocketStyles: key, separator, table
+# SupportedColonStyles: key, separator, table
+# SupportedLastArgumentHashStyles: always_inspect, always_ignore, ignore_implicit, ignore_explicit
+Layout/AlignHash:
+  Exclude:
+    - 'lib/liquid/condition.rb'
+    - 'lib/liquid/expression.rb'
+    - 'test/unit/context_unit_test.rb'
+
+# Offense count: 6
+# Cop supports --auto-correct.
+Layout/ClosingHeredocIndentation:
+  Exclude:
+    - 'test/integration/tags/for_tag_test.rb'
+
+# Offense count: 27
+# Cop supports --auto-correct.
+Layout/EmptyLineAfterGuardClause:
+  Exclude:
+    - 'lib/liquid/block.rb'
+    - 'lib/liquid/block_body.rb'
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/drop.rb'
+    - 'lib/liquid/lexer.rb'
+    - 'lib/liquid/parser.rb'
+    - 'lib/liquid/standardfilters.rb'
+    - 'lib/liquid/strainer.rb'
+    - 'lib/liquid/tags/for.rb'
+    - 'lib/liquid/tags/if.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'lib/liquid/utils.rb'
+    - 'lib/liquid/variable.rb'
+    - 'lib/liquid/variable_lookup.rb'
+
+# Offense count: 5
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: squiggly, active_support, powerpack, unindent
+Layout/IndentHeredoc:
+  Exclude:
+    - 'test/integration/tags/for_tag_test.rb'
+    - 'test/integration/trim_mode_test.rb'
+
+# Offense count: 6
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: symmetrical, new_line, same_line
+Layout/MultilineMethodCallBraceLayout:
+  Exclude:
+    - 'test/integration/error_handling_test.rb'
+    - 'test/unit/strainer_unit_test.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: AllowForAlignment.
+Layout/SpaceAroundOperators:
+  Exclude:
+    - 'lib/liquid/condition.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: runtime_error, standard_error
+Lint/InheritException:
+  Exclude:
+    - 'lib/liquid/interrupts.rb'
+
+# Offense count: 1
+# Configuration parameters: CheckForMethodsWithNoSideEffects.
+Lint/Void:
+  Exclude:
+    - 'lib/liquid/parse_context.rb'
+
+# Offense count: 53
+Metrics/AbcSize:
+  Max: 56
+
+# Offense count: 12
+Metrics/CyclomaticComplexity:
+  Max: 13
+
+# Offense count: 118
+# Configuration parameters: CountComments, ExcludedMethods.
+Metrics/MethodLength:
+  Max: 38
+
+# Offense count: 9
+Metrics/PerceivedComplexity:
+  Max: 11
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: PreferredName.
+Naming/RescuedExceptionsVariableName:
+  Exclude:
+    - 'lib/liquid/context.rb'
+
+# Offense count: 20
+# Configuration parameters: MinNameLength, AllowNamesEndingInNumbers, AllowedNames, ForbiddenNames.
+# AllowedNames: io, id, to, by, on, in, at, ip, db
+Naming/UncommunicativeMethodParamName:
+  Exclude:
+    - 'example/server/example_servlet.rb'
+    - 'lib/liquid/condition.rb'
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/standardfilters.rb'
+    - 'lib/liquid/tags/if.rb'
+    - 'lib/liquid/variable.rb'
+    - 'test/integration/filter_test.rb'
+    - 'test/integration/standard_filter_test.rb'
+    - 'test/integration/template_test.rb'
+    - 'test/unit/condition_unit_test.rb'
+
+# Offense count: 5
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: inline, group
+Style/AccessModifierDeclarations:
+  Exclude:
+    - 'lib/liquid/block_body.rb'
+    - 'lib/liquid/tag.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'test/unit/strainer_unit_test.rb'
+
+# Offense count: 10
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: prefer_alias, prefer_alias_method
+Style/Alias:
+  Exclude:
+    - 'lib/liquid/drop.rb'
+    - 'lib/liquid/i18n.rb'
+    - 'lib/liquid/profiler/hooks.rb'
+    - 'lib/liquid/standardfilters.rb'
+    - 'lib/liquid/tag.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'lib/liquid/variable.rb'
+
+# Offense count: 22
+Style/CommentedKeyword:
   Enabled: false
 
 # Offense count: 1
 # Cop supports --auto-correct.
-# Configuration parameters: MaxLineLength.
-Style/WhileUntilModifier:
+# Configuration parameters: EnforcedStyle, SingleLineConditionsOnly, IncludeTernaryExpressions.
+# SupportedStyles: assign_to_condition, assign_inside_condition
+Style/ConditionalAssignment:
+  Exclude:
+    - 'lib/liquid/errors.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/EmptyCaseCondition:
+  Exclude:
+    - 'lib/liquid/lexer.rb'
+
+# Offense count: 5
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: compact, expanded
+Style/EmptyMethod:
+  Exclude:
+    - 'lib/liquid/tag.rb'
+    - 'lib/liquid/tags/comment.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'test/integration/tags/include_tag_test.rb'
+    - 'test/unit/context_unit_test.rb'
+
+# Offense count: 3
+# Cop supports --auto-correct.
+Style/Encoding:
+  Exclude:
+    - 'lib/liquid/version.rb'
+    - 'liquid.gemspec'
+    - 'test/integration/standard_filter_test.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/ExpandPathArguments:
+  Exclude:
+    - 'Rakefile'
+    - 'liquid.gemspec'
+
+# Offense count: 7
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: annotated, template, unannotated
+Style/FormatStringToken:
+  Exclude:
+    - 'test/integration/filter_test.rb'
+    - 'test/integration/hash_ordering_test.rb'
+
+# Offense count: 106
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: always, never
+Style/FrozenStringLiteralComment:
   Enabled: false
+
+# Offense count: 14
+# Configuration parameters: MinBodyLength.
+Style/GuardClause:
+  Exclude:
+    - 'lib/liquid/condition.rb'
+    - 'lib/liquid/lexer.rb'
+    - 'lib/liquid/strainer.rb'
+    - 'lib/liquid/tags/assign.rb'
+    - 'lib/liquid/tags/capture.rb'
+    - 'lib/liquid/tags/case.rb'
+    - 'lib/liquid/tags/for.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'lib/liquid/tags/raw.rb'
+    - 'lib/liquid/tags/table_row.rb'
+    - 'lib/liquid/variable.rb'
+    - 'test/unit/tokenizer_unit_test.rb'
+
+# Offense count: 53
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: literals, strict
+Style/MutableConstant:
+  Enabled: false
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, MinBodyLength.
+# SupportedStyles: skip_modifier_ifs, always
+Style/Next:
+  Exclude:
+    - 'lib/liquid/tags/for.rb'
+
+# Offense count: 13
+# Cop supports --auto-correct.
+# Configuration parameters: AutoCorrect, EnforcedStyle, IgnoredMethods.
+# SupportedStyles: predicate, comparison
+Style/NumericPredicate:
+  Exclude:
+    - 'spec/**/*'
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/forloop_drop.rb'
+    - 'lib/liquid/standardfilters.rb'
+    - 'lib/liquid/tablerowloop_drop.rb'
+    - 'test/integration/standard_filter_test.rb'
+    - 'test/integration/template_test.rb'
+
+# Offense count: 14
+# Cop supports --auto-correct.
+# Configuration parameters: PreferredDelimiters.
+Style/PercentLiteralDelimiters:
+  Exclude:
+    - 'lib/liquid/tags/if.rb'
+    - 'liquid.gemspec'
+    - 'test/integration/assign_test.rb'
+    - 'test/integration/standard_filter_test.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/RedundantSelf:
+  Exclude:
+    - 'lib/liquid/strainer.rb'
+
+# Offense count: 3
+# Cop supports --auto-correct.
+# Configuration parameters: ConvertCodeThatCanStartToReturnNil, Whitelist.
+# Whitelist: present?, blank?, presence, try, try!
+Style/SafeNavigation:
+  Exclude:
+    - 'lib/liquid/drop.rb'
+    - 'lib/liquid/strainer.rb'
+    - 'lib/liquid/tokenizer.rb'
+
+# Offense count: 9
+# Cop supports --auto-correct.
+# Configuration parameters: AllowAsExpressionSeparator.
+Style/Semicolon:
+  Exclude:
+    - 'test/integration/error_handling_test.rb'
+    - 'test/integration/template_test.rb'
+    - 'test/unit/context_unit_test.rb'
+
+# Offense count: 7
+# Cop supports --auto-correct.
+# Configuration parameters: MinSize.
+# SupportedStyles: percent, brackets
+Style/SymbolArray:
+  EnforcedStyle: brackets
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, AllowSafeAssignment.
+# SupportedStyles: require_parentheses, require_no_parentheses, require_parentheses_when_complex
+Style/TernaryParentheses:
+  Exclude:
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/utils.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/UnneededPercentQ:
+  Exclude:
+    - 'test/integration/error_handling_test.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/WhileUntilModifier:
+  Exclude:
+    - 'lib/liquid/tags/case.rb'
+
+# Offense count: 665
+# Cop supports --auto-correct.
+# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+# URISchemes: http, https
+Metrics/LineLength:
+  Max: 294

.travis.yml

@@ -1,25 +1,28 @@
 language: ruby
 
 rvm:
-  - 2.1
-  - 2.2
-  - 2.3.3
+  - 2.4
+  - 2.5
+  - &latest_ruby 2.6
+  - 2.7
   - ruby-head
   - jruby-head
-#  - rbx-2
+  - truffleruby
 
-sudo: false
-
-addons:
-  apt:
-    packages:
-    - libgmp3-dev
 
 matrix:
+  include:
+    - rvm: *latest_ruby
+      script: bundle exec rake memory_profile:run
+      name: Profiling Memory Usage
   allow_failures:
+    - rvm: ruby-head
     - rvm: jruby-head
+    - rvm: truffleruby
 
-script: "bundle exec rake"
+cache: bundler
+
+script: bundle exec rake
 
 notifications:
   disable: true

Gemfile

@@ -1,14 +1,25 @@
 source 'https://rubygems.org'
+git_source(:github) do |repo_name|
+  "https://github.com/#{repo_name}.git"
+end
 
 gemspec
-gem 'stackprof', platforms: :mri_21
 
-group :test do
-  gem 'spy', '0.4.1'
+group :benchmark, :test do
   gem 'benchmark-ips'
-  gem 'rubocop', '0.34.2'
+  gem 'memory_profiler'
+  gem 'terminal-table'
 
-  platform :mri do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'bd53db95de3d44d631e7c5a267c3d934e66107dd'
+  install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ && RUBY_ENGINE != 'truffleruby' } do
+    gem 'stackprof'
+  end
+end
+
+group :test do
+  gem 'rubocop', '~> 0.74.0', require: false
+  gem 'rubocop-performance', require: false
+
+  platform :mri, :truffleruby do
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'liquid-tag'
   end
 end

History.md

@@ -1,6 +1,59 @@
 # Liquid Change Log
 
-## 4.0.0 / not yet released / branch "master"
+## 4.0.3 / 2019-03-12
+
+### Fixed
+* Fix break and continue tags inside included templates in loops (#1072) [Justin Li]
+
+## 4.0.2 / 2019-03-08
+
+### Changed
+* Add `where` filter (#1026) [Samuel Doiron]
+* Add `ParseTreeVisitor` to iterate the Liquid AST (#1025) [Stephen Paul Weber]
+* Improve `strip_html` performance (#1032) [printercu]
+
+### Fixed
+* Add error checking for invalid combinations of inputs to sort, sort_natural, where, uniq, map, compact filters (#1059) [Garland Zhang]
+* Validate the character encoding in url_decode (#1070) [Clayton Smith]
+
+## 4.0.1 / 2018-10-09
+
+### Changed
+* Add benchmark group in Gemfile (#855) [Jerry Liu]
+* Allow benchmarks to benchmark render by itself (#851) [Jerry Liu]
+* Avoid calling `line_number` on String node when rescuing a render error. (#860) [Dylan Thacker-Smith]
+* Avoid duck typing to detect whether to call render on a node. [Dylan Thacker-Smith]
+* Clarify spelling of `reversed` on `for` block tag (#843) [Mark Crossfield]
+* Replace recursion with loop to avoid potential stack overflow from malicious input (#891, #892) [Dylan Thacker-Smith]
+* Limit block tag nesting to 100 (#894) [Dylan Thacker-Smith]
+* Replace `assert_equal nil` with `assert_nil` (#895) [Dylan Thacker-Smith]
+* Remove Spy Gem (#896) [Dylan Thacker-Smith]
+* Add `collection_name` and `variable_name` reader to `For` block (#909)
+* Symbols render as strings (#920) [Justin Li]
+* Remove default value from Hash objects (#932) [Maxime Bedard]
+* Remove one level of nesting (#944) [Dylan Thacker-Smith]
+* Update Rubocop version (#952) [Justin Li]
+* Add `at_least` and `at_most` filters (#954, #958) [Nithin Bekal]
+* Add a regression test for a liquid-c trim mode bug (#972) [Dylan Thacker-Smith]
+* Use https rather than git protocol to fetch liquid-c [Dylan Thacker-Smith]
+* Add tests against Ruby 2.4 (#963) and 2.5 (#981)
+* Replace RegExp literals with constants (#988) [Ashwin Maroli]
+* Replace unnecessary `#each_with_index` with `#each` (#992) [Ashwin Maroli]
+* Improve the unexpected end delimiter message for block tags. (#1003) [Dylan Thacker-Smith]
+* Refactor and optimize rendering (#1005) [Christopher Aue]
+* Add installation instruction (#1006) [Ben Gift]
+* Remove Circle CI (#1010)
+* Rename deprecated `BigDecimal.new` to `BigDecimal` (#1024) [Koichi ITO]
+* Rename deprecated Rubocop name (#1027) [Justin Li]
+
+### Fixed
+* Handle `join` filter on non String joiners (#857) [Richard Monette]
+* Fix duplicate inclusion condition logic error of `Liquid::Strainer.add_filter` method (#861)
+* Fix `escape`, `url_encode`, `url_decode` not handling non-string values (#898) [Thierry Joyal]
+* Fix raise when variable is defined but nil when using `strict_variables` [Pascal Betz]
+* Fix `sort` and `sort_natural` to handle arrays with nils (#930) [Eric Chan]
+
+## 4.0.0 / 2016-12-14 / branch "4-0-stable"
 
 ### Changed
 * Render an opaque internal error by default for non-Liquid::Error (#835) [Dylan Thacker-Smith]
@@ -20,10 +73,13 @@
 * Add concat filter to concatenate arrays (#429) [Diogo Beato]
 * Ruby 1.9 support dropped (#491) [Justin Li]
 * Liquid::Template.file_system's read_template_file method is no longer passed the context. (#441) [James Reid-Smith]
-* Remove support for `liquid_methods`
+* Remove `liquid_methods` (See https://github.com/Shopify/liquid/pull/568 for replacement)
 * Liquid::Template.register_filter raises when the module overrides registered public methods as private or protected (#705) [Gaurav Chande]
 
 ### Fixed
+
+* Fix variable names being detected as an operator when starting with contains (#788) [Michael Angell]
+* Fix include tag used with strict_variables (#828) [QuickPay]
 * Fix map filter when value is a Proc (#672) [Guillaume Malette]
 * Fix truncate filter when value is not a string (#672) [Guillaume Malette]
 * Fix behaviour of escape filter when input is nil (#665) [Tanel Jakobsoo]

README.md

@@ -42,6 +42,8 @@ Liquid is a template engine which was written with very specific requirements:
 
 ## How to use Liquid
 
+Install Liquid by adding `gem 'liquid'` to your gemfile.
+
 Liquid supports a very simple API based around the Liquid::Template class.
 For standard use you can just pass it the content of a file and call render with a parameters hash.
 

Rakefile

@@ -3,7 +3,7 @@ require 'rake/testtask'
 $LOAD_PATH.unshift File.expand_path("../lib", __FILE__)
 require "liquid/version"
 
-task default: [:rubocop, :test]
+task default: [:test, :rubocop]
 
 desc 'run test suite with default parser'
 Rake::TestTask.new(:base_test) do |t|
@@ -19,8 +19,10 @@ task :warn_test do
 end
 
 task :rubocop do
-  require 'rubocop/rake_task'
-  RuboCop::RakeTask.new
+  if RUBY_ENGINE == 'ruby'
+    require 'rubocop/rake_task'
+    RuboCop::RakeTask.new
+  end
 end
 
 desc 'runs test suite with both strict and lax parsers'
@@ -32,8 +34,8 @@ task :test do
   Rake::Task['base_test'].reenable
   Rake::Task['base_test'].invoke
 
-  if RUBY_ENGINE == 'ruby'
-    ENV['LIQUID-C'] = '1'
+  if RUBY_ENGINE == 'ruby' || RUBY_ENGINE == 'truffleruby'
+    ENV['LIQUID_C'] = '1'
 
     ENV['LIQUID_PARSER_MODE'] = 'lax'
     Rake::Task['base_test'].reenable
@@ -85,6 +87,13 @@ namespace :profile do
   end
 end
 
+namespace :memory_profile do
+  desc "Run memory profiler"
+  task :run do
+    ruby "./performance/memory_profile.rb"
+  end
+end
+
 desc "Run example"
 task :example do
   ruby "-w -d -Ilib example/server/server.rb"

circle.yml

@@ -1,3 +0,0 @@
-machine:
-  ruby:
-    version: ruby-2.1

lib/liquid.rb

@@ -45,6 +45,7 @@ module Liquid
 end
 
 require "liquid/version"
+require 'liquid/parse_tree_visitor'
 require 'liquid/lexer'
 require 'liquid/parser'
 require 'liquid/i18n'
@@ -73,6 +74,7 @@ require 'liquid/condition'
 require 'liquid/utils'
 require 'liquid/tokenizer'
 require 'liquid/parse_context'
+require 'liquid/partial_cache'
 
 # Load all the tags of the standard library
 #

lib/liquid/block.rb

@@ -1,5 +1,7 @@
 module Liquid
   class Block < Tag
+    MAX_DEPTH = 100
+
     def initialize(tag_name, markup, options)
       super
       @blank = true
@@ -11,6 +13,7 @@ module Liquid
       end
     end
 
+    # For backwards compatibility
     def render(context)
       @body.render(context)
     end
@@ -24,12 +27,12 @@ module Liquid
     end
 
     def unknown_tag(tag, _params, _tokens)
-      case tag
-      when 'else'.freeze
+      if tag == 'else'.freeze
         raise SyntaxError.new(parse_context.locale.t("errors.syntax.unexpected_else".freeze,
           block_name: block_name))
-      when 'end'.freeze
+      elsif tag.start_with?('end'.freeze)
         raise SyntaxError.new(parse_context.locale.t("errors.syntax.invalid_delimiter".freeze,
+          tag: tag,
           block_name: block_name,
           block_delimiter: block_delimiter))
       else
@@ -48,17 +51,25 @@ module Liquid
     protected
 
     def parse_body(body, tokens)
-      body.parse(tokens, parse_context) do |end_tag_name, end_tag_params|
-        @blank &&= body.blank?
+      if parse_context.depth >= MAX_DEPTH
+        raise StackLevelError, "Nesting too deep".freeze
+      end
+      parse_context.depth += 1
+      begin
+        body.parse(tokens, parse_context) do |end_tag_name, end_tag_params|
+          @blank &&= body.blank?
 
-        return false if end_tag_name == block_delimiter
-        unless end_tag_name
-          raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
+          return false if end_tag_name == block_delimiter
+          unless end_tag_name
+            raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
+          end
+
+          # this tag is not registered with the system
+          # pass it to the current block for special handling or error reporting
+          unknown_tag(end_tag_name, end_tag_params, tokens)
         end
-
-        # this tag is not registered with the system
-        # pass it to the current block for special handling or error reporting
-        unknown_tag(end_tag_name, end_tag_params, tokens)
+      ensure
+        parse_context.depth -= 1
       end
 
       true

lib/liquid/block_body.rb

@@ -1,7 +1,9 @@
 module Liquid
   class BlockBody
-    FullToken = /\A#{TagStart}#{WhitespaceControl}?\s*(\w+)\s*(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
+    LiquidTagToken = /\A\s*(\w+)\s*(.*?)\z/o
+    FullToken = /\A#{TagStart}#{WhitespaceControl}?(\s*)(\w+)(\s*)(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
     ContentOfVariable = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
+    WhitespaceOrNothing = /\A\s*\z/
     TAGSTART = "{%".freeze
     VARSTART = "{{".freeze
 
@@ -12,41 +14,83 @@ module Liquid
       @blank = true
     end
 
-    def parse(tokenizer, parse_context)
+    def parse(tokenizer, parse_context, &block)
       parse_context.line_number = tokenizer.line_number
+
+      if tokenizer.for_liquid_tag
+        parse_for_liquid_tag(tokenizer, parse_context, &block)
+      else
+        parse_for_document(tokenizer, parse_context, &block)
+      end
+    end
+
+    private def parse_for_liquid_tag(tokenizer, parse_context)
       while token = tokenizer.shift
-        unless token.empty?
-          case
-          when token.start_with?(TAGSTART)
-            whitespace_handler(token, parse_context)
-            if token =~ FullToken
-              tag_name = $1
-              markup = $2
-              # fetch the tag from registered blocks
-              if tag = registered_tags[tag_name]
-                new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
-                @blank &&= new_tag.blank?
-                @nodelist << new_tag
-              else
-                # end parsing if we reach an unknown tag and let the caller decide
-                # determine how to proceed
-                return yield tag_name, markup
-              end
-            else
-              raise_missing_tag_terminator(token, parse_context)
-            end
-          when token.start_with?(VARSTART)
-            whitespace_handler(token, parse_context)
-            @nodelist << create_variable(token, parse_context)
-            @blank = false
-          else
-            if parse_context.trim_whitespace
-              token.lstrip!
-            end
-            parse_context.trim_whitespace = false
-            @nodelist << token
-            @blank &&= !!(token =~ /\A\s*\z/)
+        unless token.empty? || token =~ WhitespaceOrNothing
+          unless token =~ LiquidTagToken
+            # line isn't empty but didn't match tag syntax, yield and let the
+            # caller raise a syntax error
+            return yield token, token
           end
+          tag_name = $1
+          markup = $2
+          unless tag = registered_tags[tag_name]
+            # end parsing if we reach an unknown tag and let the caller decide
+            # determine how to proceed
+            return yield tag_name, markup
+          end
+          new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+          @blank &&= new_tag.blank?
+          @nodelist << new_tag
+        end
+        parse_context.line_number = tokenizer.line_number
+      end
+
+      yield nil, nil
+    end
+
+    private def parse_for_document(tokenizer, parse_context, &block)
+      while token = tokenizer.shift
+        next if token.empty?
+        case
+        when token.start_with?(TAGSTART)
+          whitespace_handler(token, parse_context)
+          unless token =~ FullToken
+            raise_missing_tag_terminator(token, parse_context)
+          end
+          tag_name = $2
+          markup = $4
+
+          if parse_context.line_number
+            # newlines inside the tag should increase the line number,
+            # particularly important for multiline {% liquid %} tags
+            parse_context.line_number += $1.count("\n".freeze) + $3.count("\n".freeze)
+          end
+
+          if tag_name == 'liquid'.freeze
+            liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)
+            next parse_for_liquid_tag(liquid_tag_tokenizer, parse_context, &block)
+          end
+
+          unless tag = registered_tags[tag_name]
+            # end parsing if we reach an unknown tag and let the caller decide
+            # determine how to proceed
+            return yield tag_name, markup
+          end
+          new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+          @blank &&= new_tag.blank?
+          @nodelist << new_tag
+        when token.start_with?(VARSTART)
+          whitespace_handler(token, parse_context)
+          @nodelist << create_variable(token, parse_context)
+          @blank = false
+        else
+          if parse_context.trim_whitespace
+            token.lstrip!
+          end
+          parse_context.trim_whitespace = false
+          @nodelist << token
+          @blank &&= !!(token =~ WhitespaceOrNothing)
         end
         parse_context.line_number = tokenizer.line_number
       end
@@ -69,51 +113,57 @@ module Liquid
     end
 
     def render(context)
-      output = []
+      render_to_output_buffer(context, '')
+    end
+
+    def render_to_output_buffer(context, output)
       context.resource_limits.render_score += @nodelist.length
 
-      @nodelist.each do |token|
-        # Break out if we have any unhanded interrupts.
-        break if context.interrupt?
+      idx = 0
+      while node = @nodelist[idx]
+        previous_output_size = output.bytesize
 
-        begin
+        case node
+        when String
+          output << node
+        when Variable
+          render_node(context, output, node)
+        when Block
+          render_node(context, node.blank? ? '' : output, node)
+          break if context.interrupt? # might have happened in a for-block
+        when Continue, Break
           # If we get an Interrupt that means the block must stop processing. An
           # Interrupt is any command that stops block execution such as {% break %}
           # or {% continue %}
-          if token.is_a?(Continue) || token.is_a?(Break)
-            context.push_interrupt(token.interrupt)
-            break
-          end
-
-          node_output = render_node(token, context)
-
-          unless token.is_a?(Block) && token.blank?
-            output << node_output
-          end
-        rescue MemoryError => e
-          raise e
-        rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
-          context.handle_error(e, token.line_number, token.raw)
-          output << nil
-        rescue ::StandardError => e
-          output << context.handle_error(e, token.line_number, token.raw)
+          context.push_interrupt(node.interrupt)
+          break
+        else # Other non-Block tags
+          render_node(context, output, node)
+          break if context.interrupt? # might have happened through an include
         end
+        idx += 1
+
+        raise_if_resource_limits_reached(context, output.bytesize - previous_output_size)
       end
 
-      output.join
+      output
     end
 
     private
 
-    def render_node(node, context)
-      node_output = (node.respond_to?(:render) ? node.render(context) : node)
-      node_output = node_output.is_a?(Array) ? node_output.join : node_output.to_s
+    def render_node(context, output, node)
+      node.render_to_output_buffer(context, output)
+    rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
+      context.handle_error(e, node.line_number)
+    rescue ::StandardError => e
+      line_number = node.is_a?(String) ? nil : node.line_number
+      output << context.handle_error(e, line_number)
+    end
 
-      context.resource_limits.render_length += node_output.length
-      if context.resource_limits.reached?
-        raise MemoryError.new("Memory limits exceeded".freeze)
-      end
-      node_output
+    def raise_if_resource_limits_reached(context, length)
+      context.resource_limits.render_length += length
+      return unless context.resource_limits.reached?
+      raise MemoryError.new("Memory limits exceeded".freeze)
     end
 
     def create_variable(token, parse_context)

lib/liquid/condition.rb

@@ -29,7 +29,7 @@ module Liquid
       @@operators
     end
 
-    attr_reader :attachment
+    attr_reader :attachment, :child_condition
     attr_accessor :left, :operator, :right
 
     def initialize(left = nil, operator = nil, right = nil)
@@ -41,16 +41,22 @@ module Liquid
     end
 
     def evaluate(context = Context.new)
-      result = interpret_condition(left, right, operator, context)
+      condition = self
+      result = nil
+      loop do
+        result = interpret_condition(condition.left, condition.right, condition.operator, context)
 
-      case @child_relation
-      when :or
-        result || @child_condition.evaluate(context)
-      when :and
-        result && @child_condition.evaluate(context)
-      else
-        result
+        case condition.child_relation
+        when :or
+          break if result
+        when :and
+          break unless result
+        else
+          break
+        end
+        condition = condition.child_condition
       end
+      result
     end
 
     def or(condition)
@@ -75,6 +81,10 @@ module Liquid
       "#<Condition #{[@left, @operator, @right].compact.join(' '.freeze)}>"
     end
 
+    protected
+
+    attr_reader :child_relation
+
     private
 
     def equal_variables(left, right)
@@ -110,7 +120,7 @@ module Liquid
 
       if operation.respond_to?(:call)
         operation.call(self, left, right)
-      elsif left.respond_to?(operation) && right.respond_to?(operation)
+      elsif left.respond_to?(operation) && right.respond_to?(operation) && !left.is_a?(Hash) && !right.is_a?(Hash)
         begin
           left.send(operation, right)
         rescue ::ArgumentError => e
@@ -118,6 +128,15 @@ module Liquid
         end
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.left, @node.right,
+          @node.child_condition, @node.attachment
+        ].compact
+      end
+    end
   end
 
   class ElseCondition < Condition

lib/liquid/context.rb

@@ -12,17 +12,25 @@ module Liquid
   #
   #   context['bob']  #=> nil  class Context
   class Context
-    attr_reader :scopes, :errors, :registers, :environments, :resource_limits
+    attr_reader :scopes, :errors, :registers, :environments, :resource_limits, :static_registers, :static_environments
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil)
-      @environments     = [environments].flatten
-      @scopes           = [(outer_scope || {})]
-      @registers        = registers
-      @errors           = []
-      @partial          = false
-      @strict_variables = false
-      @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
+    # rubocop:disable Metrics/ParameterLists
+    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_registers: {}, static_environments: {})
+      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_registers, static_environments)
+    end
+
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_registers = {}, static_environments = {})
+      @environments        = [environments].flatten
+      @static_environments = [static_environments].flatten.map(&:freeze).freeze
+      @scopes              = [(outer_scope || {})]
+      @registers           = registers
+      @static_registers    = static_registers.freeze
+      @errors              = []
+      @partial             = false
+      @strict_variables    = false
+      @resource_limits     = resource_limits || ResourceLimits.new(Template.default_resource_limits)
+      @base_scope_depth    = 0
       squash_instance_assigns_with_environments
 
       @this_stack_used = false
@@ -36,6 +44,7 @@ module Liquid
       @filters = []
       @global_filter = nil
     end
+    # rubocop:enable Metrics/ParameterLists
 
     def warnings
       @warnings ||= []
@@ -74,7 +83,7 @@ module Liquid
       @interrupts.pop
     end
 
-    def handle_error(e, line_number = nil, raw_token = nil)
+    def handle_error(e, line_number = nil)
       e = internal_error unless e.is_a?(Liquid::Error)
       e.template_name ||= template_name
       e.line_number ||= line_number
@@ -89,7 +98,7 @@ module Liquid
     # Push new local scope on the stack. use <tt>Context#stack</tt> instead
     def push(new_scope = {})
       @scopes.unshift(new_scope)
-      raise StackLevelError, "Nesting too deep".freeze if @scopes.length > 100
+      check_overflow
     end
 
     # Merge a hash of variables in the current local scope
@@ -126,6 +135,25 @@ module Liquid
       @this_stack_used = old_stack_used
     end
 
+    # Creates a new context inheriting resource limits, filters, environment etc.,
+    # but with an isolated scope.
+    def new_isolated_subcontext
+      check_overflow
+
+      Context.build(
+        resource_limits: resource_limits,
+        static_environments: static_environments,
+        static_registers: static_registers
+      ).tap do |subcontext|
+        subcontext.base_scope_depth = base_scope_depth + 1
+        subcontext.exception_renderer = exception_renderer
+        subcontext.filters = @filters
+        subcontext.strainer = nil
+        subcontext.errors = errors
+        subcontext.warnings = warnings
+      end
+    end
+
     def clear_instance_assigns
       @scopes[0] = {}
     end
@@ -160,35 +188,25 @@ module Liquid
     end
 
     # Fetches an object starting at the local scope and then moving up the hierachy
-    def find_variable(key)
+    def find_variable(key, raise_on_not_found: true)
       # This was changed from find() to find_index() because this is a very hot
       # path and find_index() is optimized in MRI to reduce object allocation
       index = @scopes.find_index { |s| s.key?(key) }
-      scope = @scopes[index] if index
 
-      variable = nil
-
-      if scope.nil?
-        @environments.each do |e|
-          variable = lookup_and_evaluate(e, key)
-          unless variable.nil?
-            scope = e
-            break
-          end
-        end
+      variable = if index
+        lookup_and_evaluate(@scopes[index], key, raise_on_not_found: raise_on_not_found)
+      else
+        try_variable_find_in_environments(key, raise_on_not_found: raise_on_not_found)
       end
 
-      scope ||= @environments.last || @scopes.last
-      variable ||= lookup_and_evaluate(scope, key)
-
       variable = variable.to_liquid
       variable.context = self if variable.respond_to?(:context=)
 
       variable
     end
 
-    def lookup_and_evaluate(obj, key)
-      if @strict_variables && obj.respond_to?(:key?) && !obj.key?(key)
+    def lookup_and_evaluate(obj, key, raise_on_not_found: true)
+      if @strict_variables && raise_on_not_found && obj.respond_to?(:key?) && !obj.key?(key)
         raise Liquid::UndefinedVariable, "undefined variable #{key}"
       end
 
@@ -201,8 +219,38 @@ module Liquid
       end
     end
 
+    protected
+
+    attr_writer :base_scope_depth, :warnings, :errors, :strainer, :filters
+
     private
 
+    attr_reader :base_scope_depth
+
+    def try_variable_find_in_environments(key, raise_on_not_found:)
+      @environments.each do |environment|
+        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
+        if !found_variable.nil? || @strict_variables && raise_on_not_found
+          return found_variable
+        end
+      end
+      @static_environments.each do |environment|
+        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
+        if !found_variable.nil? || @strict_variables && raise_on_not_found
+          return found_variable
+        end
+      end
+      nil
+    end
+
+    def check_overflow
+      raise StackLevelError, "Nesting too deep".freeze if overflow?
+    end
+
+    def overflow?
+      base_scope_depth + @scopes.length > Block::MAX_DEPTH
+    end
+
     def internal_error
       # raise and catch to set backtrace and cause on exception
       raise Liquid::InternalError, 'internal'

lib/liquid/expression.rb

@@ -19,22 +19,26 @@ module Liquid
       'false'.freeze => false,
       'blank'.freeze => MethodLiteral.new(:blank?, '').freeze,
       'empty'.freeze => MethodLiteral.new(:empty?, '').freeze
-    }
+    }.freeze
+
+    SINGLE_QUOTED_STRING = /\A'(.*)'\z/m
+    DOUBLE_QUOTED_STRING = /\A"(.*)"\z/m
+    INTEGERS_REGEX       = /\A(-?\d+)\z/
+    FLOATS_REGEX         = /\A(-?\d[\d\.]+)\z/
+    RANGES_REGEX         = /\A\((\S+)\.\.(\S+)\)\z/
 
     def self.parse(markup)
       if LITERALS.key?(markup)
         LITERALS[markup]
       else
         case markup
-        when /\A'(.*)'\z/m # Single quoted strings
+        when SINGLE_QUOTED_STRING, DOUBLE_QUOTED_STRING
           $1
-        when /\A"(.*)"\z/m # Double quoted strings
-          $1
-        when /\A(-?\d+)\z/ # Integer and floats
+        when INTEGERS_REGEX
           $1.to_i
-        when /\A\((\S+)\.\.(\S+)\)\z/ # Ranges
+        when RANGES_REGEX
           RangeLookup.parse($1, $2)
-        when /\A(-?\d[\d\.]+)\z/ # Floats
+        when FLOATS_REGEX
           $1.to_f
         else
           VariableLookup.parse(markup)

lib/liquid/extensions.rb

@@ -7,6 +7,12 @@ class String # :nodoc:
   end
 end
 
+class Symbol # :nodoc:
+  def to_liquid
+    to_s
+  end
+end
+
 class Array # :nodoc:
   def to_liquid
     self

lib/liquid/i18n.rb

@@ -26,7 +26,7 @@ module Liquid
     def interpolate(name, vars)
       name.gsub(/%\{(\w+)\}/) do
         # raise TranslationError, "Undefined key #{$1} for interpolation in translation #{name}"  unless vars[$1.to_sym]
-        "#{vars[$1.to_sym]}"
+        (vars[$1.to_sym]).to_s
       end
     end
 

lib/liquid/lexer.rb

@@ -12,23 +12,25 @@ module Liquid
       ')'.freeze => :close_round,
       '?'.freeze => :question,
       '-'.freeze => :dash
-    }
+    }.freeze
     IDENTIFIER = /[a-zA-Z_][\w-]*\??/
     SINGLE_STRING_LITERAL = /'[^\']*'/
     DOUBLE_STRING_LITERAL = /"[^\"]*"/
     NUMBER_LITERAL = /-?\d+(\.\d+)?/
     DOTDOT = /\.\./
-    COMPARISON_OPERATOR = /==|!=|<>|<=?|>=?|contains/
+    COMPARISON_OPERATOR = /==|!=|<>|<=?|>=?|contains(?=\s)/
+    WHITESPACE_OR_NOTHING = /\s*/
 
     def initialize(input)
-      @ss = StringScanner.new(input.rstrip)
+      @ss = StringScanner.new(input)
     end
 
     def tokenize
       @output = []
 
       until @ss.eos?
-        @ss.skip(/\s*/)
+        @ss.skip(WHITESPACE_OR_NOTHING)
+        break if @ss.eos?
         tok = case
         when t = @ss.scan(COMPARISON_OPERATOR) then [:comparison, t]
         when t = @ss.scan(SINGLE_STRING_LITERAL) then [:string, t]

lib/liquid/locales/en.yml

@@ -14,7 +14,7 @@
       if: "Syntax Error in tag 'if' - Valid syntax: if [expression]"
       include: "Error in tag 'include' - Valid syntax: include '[template]' (with|for) [object|collection]"
       unknown_tag: "Unknown tag '%{tag}'"
-      invalid_delimiter: "'end' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
+      invalid_delimiter: "'%{tag}' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
       unexpected_else: "%{block_name} tag does not expect 'else' tag"
       unexpected_outer_tag: "Unexpected outer '%{tag}' tag"
       tag_termination: "Tag '%{token}' was not properly terminated with regexp: %{tag_end}"
@@ -22,5 +22,6 @@
       tag_never_closed: "'%{block_name}' tag was never closed"
       meta_syntax_error: "Liquid syntax error: #{e.message}"
       table_row: "Syntax Error in 'table_row loop' - Valid syntax: table_row [item] in [collection] cols=3"
+      render: "Syntax error in tag 'render' - Template name must be a quoted string"
     argument:
       include: "Argument error in tag 'include' - Illegal template name"

lib/liquid/parse_context.rb

@@ -1,12 +1,13 @@
 module Liquid
   class ParseContext
-    attr_accessor :locale, :line_number, :trim_whitespace
+    attr_accessor :locale, :line_number, :trim_whitespace, :depth
     attr_reader :partial, :warnings, :error_mode
 
     def initialize(options = {})
       @template_options = options ? options.dup : {}
       @locale = @template_options[:locale] ||= I18n.new
       @warnings = []
+      self.depth = 0
       self.partial = false
     end
 

lib/liquid/parse_tree_visitor.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Liquid
+  class ParseTreeVisitor
+    def self.for(node, callbacks = Hash.new(proc {}))
+      if defined?(node.class::ParseTreeVisitor)
+        node.class::ParseTreeVisitor
+      else
+        self
+      end.new(node, callbacks)
+    end
+
+    def initialize(node, callbacks)
+      @node = node
+      @callbacks = callbacks
+    end
+
+    def add_callback_for(*classes, &block)
+      callback = block
+      callback = ->(node, _) { yield node } if block.arity.abs == 1
+      callback = ->(_, _) { yield } if block.arity.zero?
+      classes.each { |klass| @callbacks[klass] = callback }
+      self
+    end
+
+    def visit(context = nil)
+      children.map do |node|
+        item, new_context = @callbacks[node.class].call(node, context)
+        [
+          item,
+          ParseTreeVisitor.for(node, @callbacks).visit(new_context || context)
+        ]
+      end
+    end
+
+    protected
+
+    def children
+      @node.respond_to?(:nodelist) ? Array(@node.nodelist) : []
+    end
+  end
+end

lib/liquid/parser.rb

@@ -44,11 +44,14 @@ module Liquid
       tok[0] == type
     end
 
+    SINGLE_TOKEN_EXPRESSION_TYPES = [:string, :number].freeze
+    private_constant :SINGLE_TOKEN_EXPRESSION_TYPES
+
     def expression
       token = @tokens[@p]
       if token[0] == :id
         variable_signature
-      elsif [:string, :number].include? token[0]
+      elsif SINGLE_TOKEN_EXPRESSION_TYPES.include? token[0]
         consume
       elsif token.first == :open_round
         consume

lib/liquid/partial_cache.rb

@@ -0,0 +1,18 @@
+module Liquid
+  class PartialCache
+    def self.load(template_name, context:, parse_context:)
+      cached_partials = (context.registers[:cached_partials] ||= {})
+      cached = cached_partials[template_name]
+      return cached if cached
+
+      file_system = (context.registers[:file_system] ||= Liquid::Template.file_system)
+      source = file_system.read_template_file(template_name)
+      parse_context.partial = true
+
+      partial = Liquid::Template.parse(source, parse_context)
+      cached_partials[template_name] = partial
+    ensure
+      parse_context.partial = false
+    end
+  end
+end

lib/liquid/profiler/hooks.rb

@@ -1,8 +1,8 @@
 module Liquid
   class BlockBody
-    def render_node_with_profiling(node, context)
+    def render_node_with_profiling(context, output, node)
       Profiler.profile_node_render(node) do
-        render_node_without_profiling(node, context)
+        render_node_without_profiling(context, output, node)
       end
     end
 
@@ -11,13 +11,13 @@ module Liquid
   end
 
   class Include < Tag
-    def render_with_profiling(context)
+    def render_to_output_buffer_with_profiling(context, output)
       Profiler.profile_children(context.evaluate(@template_name_expr).to_s) do
-        render_without_profiling(context)
+        render_to_output_buffer_without_profiling(context, output)
       end
     end
 
-    alias_method :render_without_profiling, :render
-    alias_method :render, :render_with_profiling
+    alias_method :render_to_output_buffer_without_profiling, :render_to_output_buffer
+    alias_method :render_to_output_buffer, :render_to_output_buffer_with_profiling
   end
 end

lib/liquid/standardfilters.rb

@@ -9,8 +9,14 @@ module Liquid
       '<'.freeze => '&lt;'.freeze,
       '"'.freeze => '&quot;'.freeze,
       "'".freeze => '&#39;'.freeze
-    }
+    }.freeze
     HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/
+    STRIP_HTML_BLOCKS = Regexp.union(
+      /<script.*?<\/script>/m,
+      /<!--.*?-->/m,
+      /<style.*?<\/style>/m
+    )
+    STRIP_HTML_TAGS = /<.*?>/m
 
     # Return the size of an array or of an string
     def size(input)
@@ -33,7 +39,7 @@ module Liquid
     end
 
     def escape(input)
-      CGI.escapeHTML(input).untaint unless input.nil?
+      CGI.escapeHTML(input.to_s).untaint unless input.nil?
     end
     alias_method :h, :escape
 
@@ -42,11 +48,16 @@ module Liquid
     end
 
     def url_encode(input)
-      CGI.escape(input) unless input.nil?
+      CGI.escape(input.to_s) unless input.nil?
     end
 
     def url_decode(input)
-      CGI.unescape(input) unless input.nil?
+      return if input.nil?
+
+      result = CGI.unescape(input.to_s)
+      raise Liquid::ArgumentError, "invalid byte sequence in #{result.encoding}" unless result.valid_encoding?
+
+      result
     end
 
     def slice(input, offset, length = nil)
@@ -68,7 +79,7 @@ module Liquid
       truncate_string_str = truncate_string.to_s
       l = length - truncate_string_str.length
       l = 0 if l < 0
-      input_str.length > length ? input_str[0...l] + truncate_string_str : input_str
+      input_str.length > length ? input_str[0...l].concat(truncate_string_str) : input_str
     end
 
     def truncatewords(input, words = 15, truncate_string = "...".freeze)
@@ -77,7 +88,7 @@ module Liquid
       words = Utils.to_integer(words)
       l = words - 1
       l = 0 if l < 0
-      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string.to_s : input
+      wordlist.length > l ? wordlist[0..l].join(" ".freeze).concat(truncate_string.to_s) : input
     end
 
     # Split input string into an array of substrings separated by given pattern.
@@ -103,7 +114,9 @@ module Liquid
 
     def strip_html(input)
       empty = ''.freeze
-      input.to_s.gsub(/<script.*?<\/script>/m, empty).gsub(/<!--.*?-->/m, empty).gsub(/<style.*?<\/style>/m, empty).gsub(/<.*?>/m, empty)
+      result = input.to_s.gsub(STRIP_HTML_BLOCKS, empty)
+      result.gsub!(STRIP_HTML_TAGS, empty)
+      result
     end
 
     # Remove all newlines from the string
@@ -120,19 +133,18 @@ module Liquid
     # provide optional property with which to sort an array of hashes or drops
     def sort(input, property = nil)
       ary = InputIterator.new(input)
+
+      return [] if ary.empty?
+
       if property.nil?
-        ary.sort
-      elsif ary.empty? # The next two cases assume a non-empty array.
-        []
-      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
         ary.sort do |a, b|
-          a = a[property]
-          b = b[property]
-          if a && b
-            a <=> b
-          else
-            a ? -1 : 1
-          end
+          nil_safe_compare(a, b)
+        end
+      elsif ary.all? { |el| el.respond_to?(:[]) }
+        begin
+          ary.sort { |a, b| nil_safe_compare(a[property], b[property]) }
+        rescue TypeError
+          raise_property_error(property)
         end
       end
     end
@@ -142,12 +154,40 @@ module Liquid
     def sort_natural(input, property = nil)
       ary = InputIterator.new(input)
 
+      return [] if ary.empty?
+
       if property.nil?
-        ary.sort { |a, b| a.casecmp(b) }
-      elsif ary.empty? # The next two cases assume a non-empty array.
+        ary.sort do |a, b|
+          nil_safe_casecmp(a, b)
+        end
+      elsif ary.all? { |el| el.respond_to?(:[]) }
+        begin
+          ary.sort { |a, b| nil_safe_casecmp(a[property], b[property]) }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      end
+    end
+
+    # Filter the elements of an array to those with a certain property value.
+    # By default the target is any truthy value.
+    def where(input, property, target_value = nil)
+      ary = InputIterator.new(input)
+
+      if ary.empty?
         []
-      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
-        ary.sort { |a, b| a[property].casecmp(b[property]) }
+      elsif ary.first.respond_to?(:[]) && target_value.nil?
+        begin
+          ary.select { |item| item[property] }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      elsif ary.first.respond_to?(:[])
+        begin
+          ary.select { |item| item[property] == target_value }
+        rescue TypeError
+          raise_property_error(property)
+        end
       end
     end
 
@@ -161,7 +201,11 @@ module Liquid
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
       elsif ary.first.respond_to?(:[])
-        ary.uniq{ |a| a[property] }
+        begin
+          ary.uniq { |a| a[property] }
+        rescue TypeError
+          raise_property_error(property)
+        end
       end
     end
 
@@ -183,6 +227,8 @@ module Liquid
           r.is_a?(Proc) ? r.call : r
         end
       end
+    rescue TypeError
+      raise_property_error(property)
     end
 
     # Remove nils within an array
@@ -195,7 +241,11 @@ module Liquid
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
       elsif ary.first.respond_to?(:[])
-        ary.reject{ |a| a[property].nil? }
+        begin
+          ary.reject { |a| a[property].nil? }
+        rescue TypeError
+          raise_property_error(property)
+        end
       end
     end
 
@@ -353,6 +403,22 @@ module Liquid
       raise Liquid::FloatDomainError, e.message
     end
 
+    def at_least(input, n)
+      min_value = Utils.to_number(n)
+
+      result = Utils.to_number(input)
+      result = min_value if min_value > result
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
+    def at_most(input, n)
+      max_value = Utils.to_number(n)
+
+      result = Utils.to_number(input)
+      result = max_value if max_value < result
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
     def default(input, default_value = ''.freeze)
       if !input || input.respond_to?(:empty?) && input.empty?
         default_value
@@ -363,11 +429,31 @@ module Liquid
 
     private
 
+    def raise_property_error(property)
+      raise Liquid::ArgumentError.new("cannot select the property '#{property}'")
+    end
+
     def apply_operation(input, operand, operation)
       result = Utils.to_number(input).send(operation, Utils.to_number(operand))
       result.is_a?(BigDecimal) ? result.to_f : result
     end
 
+    def nil_safe_compare(a, b)
+      if !a.nil? && !b.nil?
+        a <=> b
+      else
+        a.nil? ? 1 : -1
+      end
+    end
+
+    def nil_safe_casecmp(a, b)
+      if !a.nil? && !b.nil?
+        a.to_s.casecmp(b.to_s)
+      else
+        a.nil? ? 1 : -1
+      end
+    end
+
     class InputIterator
       include Enumerable
 
@@ -384,7 +470,7 @@ module Liquid
       end
 
       def join(glue)
-        to_a.join(glue)
+        to_a.join(glue.to_s)
       end
 
       def concat(args)

lib/liquid/strainer.rb

@@ -27,7 +27,7 @@ module Liquid
 
     def self.add_filter(filter)
       raise ArgumentError, "Expected module but got: #{filter.class}" unless filter.is_a?(Module)
-      unless self.class.include?(filter)
+      unless self.include?(filter)
         invokable_non_public_methods = (filter.private_instance_methods + filter.protected_instance_methods).select { |m| invokable?(m) }
         if invokable_non_public_methods.any?
           raise MethodOverrideError, "Filter overrides registered public methods as non public: #{invokable_non_public_methods.join(', ')}"

lib/liquid/tag.rb

@@ -5,8 +5,8 @@ module Liquid
     include ParserSwitching
 
     class << self
-      def parse(tag_name, markup, tokenizer, options)
-        tag = new(tag_name, markup, options)
+      def parse(tag_name, markup, tokenizer, parse_context)
+        tag = new(tag_name, markup, parse_context)
         tag.parse(tokenizer)
         tag
       end
@@ -36,6 +36,14 @@ module Liquid
       ''.freeze
     end
 
+    # For backwards compatibility with custom tags. In a future release, the semantics
+    # of the `render_to_output_buffer` method will become the default and the `render`
+    # method will be removed.
+    def render_to_output_buffer(context, output)
+      output << render(context)
+      output
+    end
+
     def blank?
       false
     end

lib/liquid/tags/assign.rb

@@ -10,21 +10,27 @@ module Liquid
   class Assign < Tag
     Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
 
+    def self.syntax_error_translation_key
+      "errors.syntax.assign".freeze
+    end
+
+    attr_reader :to, :from
+
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
         @to = $1
         @from = Variable.new($2, options)
       else
-        raise SyntaxError.new options[:locale].t("errors.syntax.assign".freeze)
+        raise SyntaxError.new(options[:locale].t(self.class.syntax_error_translation_key))
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       val = @from.render(context)
       context.scopes.last[@to] = val
       context.resource_limits.assign_score += assign_score_of(val)
-      ''.freeze
+      output
     end
 
     def blank?
@@ -35,7 +41,7 @@ module Liquid
 
     def assign_score_of(val)
       if val.instance_of?(String)
-        val.length
+        val.bytesize
       elsif val.instance_of?(Array) || val.instance_of?(Hash)
         sum = 1
         # Uses #each to avoid extra allocations.
@@ -45,6 +51,12 @@ module Liquid
         1
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.from]
+      end
+    end
   end
 
   Template.register_tag('assign'.freeze, Assign)

lib/liquid/tags/capture.rb

@@ -22,11 +22,12 @@ module Liquid
       end
     end
 
-    def render(context)
-      output = super
+    def render_to_output_buffer(context, output)
+      previous_output_size = output.bytesize
+      super
       context.scopes.last[@to] = output
-      context.resource_limits.assign_score += output.length
-      ''.freeze
+      context.resource_limits.assign_score += (output.bytesize - previous_output_size)
+      output
     end
 
     def blank?

lib/liquid/tags/case.rb

@@ -3,6 +3,8 @@ module Liquid
     Syntax     = /(#{QuotedFragment})/o
     WhenSyntax = /(#{QuotedFragment})(?:(?:\s+or\s+|\s*\,\s*)(#{QuotedFragment}.*))?/om
 
+    attr_reader :blocks, :left
+
     def initialize(tag_name, markup, options)
       super
       @blocks = []
@@ -36,21 +38,21 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
         execute_else_block = true
 
-        output = ''
         @blocks.each do |block|
           if block.else?
-            return block.attachment.render(context) if execute_else_block
+            block.attachment.render_to_output_buffer(context, output) if execute_else_block
           elsif block.evaluate(context)
             execute_else_block = false
-            output << block.attachment.render(context)
+            block.attachment.render_to_output_buffer(context, output)
           end
         end
-        output
       end
+
+      output
     end
 
     private
@@ -80,6 +82,12 @@ module Liquid
       block.attach(BlockBody.new)
       @blocks << block
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.left] + @node.blocks
+      end
+    end
   end
 
   Template.register_tag('case'.freeze, Case)

lib/liquid/tags/comment.rb

@@ -1,7 +1,7 @@
 module Liquid
   class Comment < Block
-    def render(_context)
-      ''.freeze
+    def render_to_output_buffer(_context, output)
+      output
     end
 
     def unknown_tag(_tag, _markup, _tokens)

lib/liquid/tags/cycle.rb

@@ -15,6 +15,8 @@ module Liquid
     SimpleSyntax = /\A#{QuotedFragment}+/o
     NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
 
+    attr_reader :variables
+
     def initialize(tag_name, markup, options)
       super
       case markup
@@ -29,18 +31,29 @@ module Liquid
       end
     end
 
-    def render(context)
-      context.registers[:cycle] ||= Hash.new(0)
+    def render_to_output_buffer(context, output)
+      context.registers[:cycle] ||= {}
 
       context.stack do
         key = context.evaluate(@name)
-        iteration = context.registers[:cycle][key]
-        result = context.evaluate(@variables[iteration])
+        iteration = context.registers[:cycle][key].to_i
+
+        val = context.evaluate(@variables[iteration])
+
+        if val.is_a?(Array)
+          val = val.join
+        elsif !val.is_a?(String)
+          val = val.to_s
+        end
+
+        output << val
+
         iteration += 1
         iteration  = 0 if iteration >= @variables.size
         context.registers[:cycle][key] = iteration
-        result
       end
+
+      output
     end
 
     private
@@ -51,6 +64,12 @@ module Liquid
         $1 ? Expression.parse($1) : nil
       end.compact
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        Array(@node.variables)
+      end
+    end
   end
 
   Template.register_tag('cycle', Cycle)

lib/liquid/tags/decrement.rb

@@ -23,11 +23,12 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       value -= 1
       context.environments.first[@variable] = value
-      value.to_s
+      output << value.to_s
+      output
     end
   end
 

lib/liquid/tags/echo.rb

@@ -0,0 +1,24 @@
+module Liquid
+  # Echo outputs an expression
+  #
+  #   {% echo monkey %}
+  #   {% echo user.name %}
+  #
+  # This is identical to variable output syntax, like {{ foo }}, but works
+  # inside {% liquid %} tags. The full syntax is supported, including filters:
+  #
+  #   {% echo user | link %}
+  #
+  class Echo < Tag
+    def initialize(tag_name, markup, parse_context)
+      super
+      @variable = Variable.new(markup, parse_context)
+    end
+
+    def render(context)
+      @variable.render_to_output_buffer(context, '')
+    end
+  end
+
+  Template.register_tag('echo'.freeze, Echo)
+end

lib/liquid/tags/for.rb

@@ -23,7 +23,7 @@ module Liquid
   #      {{ item.name }}
   #    {% end %}
   #
-  #  To reverse the for loop simply use {% for item in collection reversed %}
+  #  To reverse the for loop simply use {% for item in collection reversed %} (note that the flag's spelling is different to the filter `reverse`)
   #
   # == Available variables:
   #
@@ -46,6 +46,8 @@ module Liquid
   class For < Block
     Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
 
+    attr_reader :collection_name, :variable_name, :limit, :from
+
     def initialize(tag_name, markup, options)
       super
       @from = @limit = nil
@@ -68,14 +70,16 @@ module Liquid
       @else_block = BlockBody.new
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       segment = collection_segment(context)
 
       if segment.empty?
-        render_else(context)
+        render_else(context, output)
       else
-        render_segment(context, segment)
+        render_segment(context, output, segment)
       end
+
+      output
     end
 
     protected
@@ -117,19 +121,28 @@ module Liquid
     private
 
     def collection_segment(context)
-      offsets = context.registers[:for] ||= Hash.new(0)
+      offsets = context.registers[:for] ||= {}
 
       from = if @from == :continue
         offsets[@name].to_i
       else
-        context.evaluate(@from).to_i
+        from_value = context.evaluate(@from)
+        if from_value.nil?
+          0
+        else
+          Utils.to_integer(from_value)
+        end
       end
 
       collection = context.evaluate(@collection_name)
       collection = collection.to_a if collection.is_a?(Range)
 
-      limit = context.evaluate(@limit)
-      to = limit ? limit.to_i + from : nil
+      limit_value = context.evaluate(@limit)
+      to = if limit_value.nil?
+        nil
+      else
+        Utils.to_integer(limit_value) + from
+      end
 
       segment = Utils.slice_collection(collection, from, to)
       segment.reverse! if @reversed
@@ -139,12 +152,10 @@ module Liquid
       segment
     end
 
-    def render_segment(context, segment)
+    def render_segment(context, output, segment)
       for_stack = context.registers[:for_stack] ||= []
       length = segment.length
 
-      result = ''
-
       context.stack do
         loop_vars = Liquid::ForloopDrop.new(@name, length, for_stack[-1])
 
@@ -153,9 +164,9 @@ module Liquid
         begin
           context['forloop'.freeze] = loop_vars
 
-          segment.each_with_index do |item, index|
+          segment.each do |item|
             context[@variable_name] = item
-            result << @for_block.render(context)
+            @for_block.render_to_output_buffer(context, output)
             loop_vars.send(:increment!)
 
             # Handle any interrupts if they exist.
@@ -170,7 +181,7 @@ module Liquid
         end
       end
 
-      result
+      output
     end
 
     def set_attribute(key, expr)
@@ -186,8 +197,18 @@ module Liquid
       end
     end
 
-    def render_else(context)
-      @else_block ? @else_block.render(context) : ''.freeze
+    def render_else(context, output)
+      if @else_block
+        @else_block.render_to_output_buffer(context, output)
+      else
+        output
+      end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        (super + [@node.limit, @node.from, @node.collection_name]).compact
+      end
     end
   end
 

lib/liquid/tags/if.rb

@@ -12,7 +12,9 @@ module Liquid
   class If < Block
     Syntax = /(#{QuotedFragment})\s*([=!<>a-z_]+)?\s*(#{QuotedFragment})?/o
     ExpressionsAndOperators = /(?:\b(?:\s?and\s?|\s?or\s?)\b|(?:\s*(?!\b(?:\s?and\s?|\s?or\s?)\b)(?:#{QuotedFragment}|\S+)\s*)+)/o
-    BOOLEAN_OPERATORS = %w(and or)
+    BOOLEAN_OPERATORS = %w(and or).freeze
+
+    attr_reader :blocks
 
     def initialize(tag_name, markup, options)
       super
@@ -20,15 +22,15 @@ module Liquid
       push_block('if'.freeze, markup)
     end
 
+    def nodelist
+      @blocks.map(&:attachment)
+    end
+
     def parse(tokens)
       while parse_body(@blocks.last.attachment, tokens)
       end
     end
 
-    def nodelist
-      @blocks.map(&:attachment)
-    end
-
     def unknown_tag(tag, markup, tokens)
       if ['elsif'.freeze, 'else'.freeze].include?(tag)
         push_block(tag, markup)
@@ -37,15 +39,16 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
         @blocks.each do |block|
           if block.evaluate(context)
-            return block.attachment.render(context)
+            return block.attachment.render_to_output_buffer(context, output)
           end
         end
-        ''.freeze
       end
+
+      output
     end
 
     private
@@ -83,17 +86,20 @@ module Liquid
 
     def strict_parse(markup)
       p = Parser.new(markup)
-      condition = parse_binary_comparison(p)
+      condition = parse_binary_comparisons(p)
       p.consume(:end_of_string)
       condition
     end
 
-    def parse_binary_comparison(p)
+    def parse_binary_comparisons(p)
       condition = parse_comparison(p)
-      if op = (p.id?('and'.freeze) || p.id?('or'.freeze))
-        condition.send(op, parse_binary_comparison(p))
+      first_condition = condition
+      while op = (p.id?('and'.freeze) || p.id?('or'.freeze))
+        child_condition = parse_comparison(p)
+        condition.send(op, child_condition)
+        condition = child_condition
       end
-      condition
+      first_condition
     end
 
     def parse_comparison(p)
@@ -105,6 +111,12 @@ module Liquid
         Condition.new(a)
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.blocks
+      end
+    end
   end
 
   Template.register_tag('if'.freeze, If)

lib/liquid/tags/ifchanged.rb

@@ -1,16 +1,17 @@
 module Liquid
   class Ifchanged < Block
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
-        output = super
+        block_output = ''
+        super(context, block_output)
 
-        if output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = output
-          output
-        else
-          ''.freeze
+        if block_output != context.registers[:ifchanged]
+          context.registers[:ifchanged] = block_output
+          output << block_output
         end
       end
+
+      output
     end
   end
 

lib/liquid/tags/include.rb

@@ -16,6 +16,8 @@ module Liquid
   class Include < Tag
     Syntax = /(#{QuotedFragment}+)(\s+(?:with|for)\s+(#{QuotedFragment}+))?/o
 
+    attr_reader :template_name_expr, :variable_name_expr, :attributes
+
     def initialize(tag_name, markup, options)
       super
 
@@ -40,17 +42,22 @@ module Liquid
     def parse(_tokens)
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       template_name = context.evaluate(@template_name_expr)
       raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
 
-      partial = load_cached_partial(template_name, context)
+      partial = PartialCache.load(
+        template_name,
+        context: context,
+        parse_context: parse_context
+      )
+
       context_variable_name = template_name.split('/'.freeze).last
 
       variable = if @variable_name_expr
         context.evaluate(@variable_name_expr)
       else
-        context.find_variable(template_name)
+        context.find_variable(template_name, raise_on_not_found: false)
       end
 
       old_template_name = context.template_name
@@ -64,48 +71,33 @@ module Liquid
           end
 
           if variable.is_a?(Array)
-            variable.collect do |var|
+            variable.each do |var|
               context[context_variable_name] = var
-              partial.render(context)
+              partial.render_to_output_buffer(context, output)
             end
           else
             context[context_variable_name] = variable
-            partial.render(context)
+            partial.render_to_output_buffer(context, output)
           end
         end
       ensure
         context.template_name = old_template_name
         context.partial = old_partial
       end
-    end
 
-    private
+      output
+    end
 
     alias_method :parse_context, :options
     private :parse_context
 
-    def load_cached_partial(template_name, context)
-      cached_partials = context.registers[:cached_partials] || {}
-
-      if cached = cached_partials[template_name]
-        return cached
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.template_name_expr,
+          @node.variable_name_expr
+        ] + @node.attributes.values
       end
-      source = read_template_from_file_system(context)
-      begin
-        parse_context.partial = true
-        partial = Liquid::Template.parse(source, parse_context)
-      ensure
-        parse_context.partial = false
-      end
-      cached_partials[template_name] = partial
-      context.registers[:cached_partials] = cached_partials
-      partial
-    end
-
-    def read_template_from_file_system(context)
-      file_system = context.registers[:file_system] || Liquid::Template.file_system
-
-      file_system.read_template_file(context.evaluate(@template_name_expr))
     end
   end
 

lib/liquid/tags/increment.rb

@@ -20,10 +20,12 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       context.environments.first[@variable] = value + 1
-      value.to_s
+
+      output << value.to_s
+      output
     end
   end
 

lib/liquid/tags/raw.rb

@@ -22,8 +22,9 @@ module Liquid
       raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
     end
 
-    def render(_context)
-      @body
+    def render_to_output_buffer(_context, output)
+      output << @body
+      output
     end
 
     def nodelist

lib/liquid/tags/render.rb

@@ -0,0 +1,54 @@
+module Liquid
+  class Render < Tag
+    Syntax = /(#{QuotedString})#{QuotedFragment}*/o
+
+    attr_reader :template_name_expr, :attributes
+
+    def initialize(tag_name, markup, options)
+      super
+
+      raise SyntaxError.new(options[:locale].t("errors.syntax.render".freeze)) unless markup =~ Syntax
+
+      template_name = $1
+
+      @template_name_expr = Expression.parse(template_name)
+
+      @attributes = {}
+      markup.scan(TagAttributes) do |key, value|
+        @attributes[key] = Expression.parse(value)
+      end
+    end
+
+    def render_to_output_buffer(context, output)
+      # Though we evaluate this here we will only ever parse it as a string literal.
+      template_name = context.evaluate(@template_name_expr)
+      raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
+
+      partial = PartialCache.load(
+        template_name,
+        context: context,
+        parse_context: parse_context
+      )
+
+      inner_context = context.new_isolated_subcontext
+      inner_context.template_name = template_name
+      inner_context.partial = true
+      @attributes.each do |key, value|
+        inner_context[key] = context.evaluate(value)
+      end
+      partial.render_to_output_buffer(inner_context, output)
+
+      output
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.template_name_expr,
+        ] + @node.attributes.values
+      end
+    end
+  end
+
+  Template.register_tag('render'.freeze, Render)
+end

lib/liquid/tags/table_row.rb

@@ -2,6 +2,8 @@ module Liquid
   class TableRow < Block
     Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
 
+    attr_reader :variable_name, :collection_name, :attributes
+
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
@@ -16,7 +18,7 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       collection = context.evaluate(@collection_name) or return ''.freeze
 
       from = @attributes.key?('offset'.freeze) ? context.evaluate(@attributes['offset'.freeze]).to_i : 0
@@ -28,25 +30,34 @@ module Liquid
 
       cols = context.evaluate(@attributes['cols'.freeze]).to_i
 
-      result = "<tr class=\"row1\">\n"
+      output << "<tr class=\"row1\">\n"
       context.stack do
         tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
         context['tablerowloop'.freeze] = tablerowloop
 
-        collection.each_with_index do |item, index|
+        collection.each do |item|
           context[@variable_name] = item
 
-          result << "<td class=\"col#{tablerowloop.col}\">" << super << '</td>'
+          output << "<td class=\"col#{tablerowloop.col}\">"
+          super
+          output << '</td>'
 
           if tablerowloop.col_last && !tablerowloop.last
-            result << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
+            output << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
           end
 
           tablerowloop.send(:increment!)
         end
       end
-      result << "</tr>\n"
-      result
+
+      output << "</tr>\n"
+      output
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        super + @node.attributes.values + [@node.collection_name]
+      end
     end
   end
 

lib/liquid/tags/unless.rb

@@ -6,23 +6,23 @@ module Liquid
   #   {% unless x < 0 %} x is greater than zero {% endunless %}
   #
   class Unless < If
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
         # First condition is interpreted backwards ( if not )
         first_block = @blocks.first
         unless first_block.evaluate(context)
-          return first_block.attachment.render(context)
+          return first_block.attachment.render_to_output_buffer(context, output)
         end
 
         # After the first condition unless works just like if
         @blocks[1..-1].each do |block|
           if block.evaluate(context)
-            return block.attachment.render(context)
+            return block.attachment.render_to_output_buffer(context, output)
           end
         end
-
-        ''.freeze
       end
+
+      output
     end
   end
 

lib/liquid/template.rb

@@ -50,7 +50,7 @@ module Liquid
       private
 
       def lookup_class(name)
-        name.split("::").reject(&:empty?).reduce(Object) { |scope, const| scope.const_get(const) }
+        Object.const_get(name)
       end
     end
 
@@ -187,9 +187,12 @@ module Liquid
         raise ArgumentError, "Expected Hash or Liquid::Context as parameter"
       end
 
+      output = nil
+
       case args.last
       when Hash
         options = args.pop
+        output = options[:output] if options[:output]
 
         registers.merge!(options[:registers]) if options[:registers].is_a?(Hash)
 
@@ -204,10 +207,9 @@ module Liquid
       begin
         # render the nodelist.
         # for performance reasons we get an array back here. join will make a string out of it.
-        result = with_profiling(context) do
-          @root.render(context)
+        with_profiling(context) do
+          @root.render_to_output_buffer(context, output || '')
         end
-        result.respond_to?(:join) ? result.join : result
       rescue Liquid::MemoryError => e
         context.handle_error(e)
       ensure
@@ -220,6 +222,10 @@ module Liquid
       render(*args)
     end
 
+    def render_to_output_buffer(context, output)
+      render(context, output: output)
+    end
+
     private
 
     def tokenize(source)

lib/liquid/tokenizer.rb

@@ -1,25 +1,31 @@
 module Liquid
   class Tokenizer
-    attr_reader :line_number
+    attr_reader :line_number, :for_liquid_tag
 
-    def initialize(source, line_numbers = false)
+    def initialize(source, line_numbers = false, line_number: nil, for_liquid_tag: false)
       @source = source
-      @line_number = line_numbers ? 1 : nil
+      @line_number = line_number || (line_numbers ? 1 : nil)
+      @for_liquid_tag = for_liquid_tag
       @tokens = tokenize
     end
 
     def shift
-      token = @tokens.shift
-      @line_number += token.count("\n") if @line_number && token
+      token = @tokens.shift or return
+
+      if @line_number
+        @line_number += @for_liquid_tag ? 1 : token.count("\n")
+      end
+
       token
     end
 
     private
 
     def tokenize
-      @source = @source.source if @source.respond_to?(:source)
       return [] if @source.to_s.empty?
 
+      return @source.split("\n") if @for_liquid_tag
+
       tokens = @source.split(TemplateParser)
 
       # removes the rogue empty element at the beginning of the array

lib/liquid/utils.rb

@@ -46,11 +46,11 @@ module Liquid
     def self.to_number(obj)
       case obj
       when Float
-        BigDecimal.new(obj.to_s)
+        BigDecimal(obj.to_s)
       when Numeric
         obj
       when String
-        (obj.strip =~ /\A-?\d+\.\d+\z/) ? BigDecimal.new(obj) : obj.to_i
+        (obj.strip =~ /\A-?\d+\.\d+\z/) ? BigDecimal(obj) : obj.to_i
       else
         if obj.respond_to?(:to_number)
           obj.to_number

lib/liquid/variable.rb

@@ -10,10 +10,16 @@ module Liquid
   #   {{ user | link }}
   #
   class Variable
+    FilterMarkupRegex = /#{FilterSeparator}\s*(.*)/om
     FilterParser = /(?:\s+|#{QuotedFragment}|#{ArgumentSeparator})+/o
+    FilterArgsRegex = /(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o
+    JustTagAttributes = /\A#{TagAttributes}\z/o
+    MarkupWithQuotedFragment = /(#{QuotedFragment})(.*)/om
+
     attr_accessor :filters, :name, :line_number
     attr_reader :parse_context
     alias_method :options, :parse_context
+
     include ParserSwitching
 
     def initialize(markup, parse_context)
@@ -35,17 +41,17 @@ module Liquid
 
     def lax_parse(markup)
       @filters = []
-      return unless markup =~ /(#{QuotedFragment})(.*)/om
+      return unless markup =~ MarkupWithQuotedFragment
 
       name_markup = $1
       filter_markup = $2
       @name = Expression.parse(name_markup)
-      if filter_markup =~ /#{FilterSeparator}\s*(.*)/om
+      if filter_markup =~ FilterMarkupRegex
         filters = $1.scan(FilterParser)
         filters.each do |f|
           next unless f =~ /\w+/
           filtername = Regexp.last_match(0)
-          filterargs = f.scan(/(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o).flatten
+          filterargs = f.scan(FilterArgsRegex).flatten
           @filters << parse_filter_expressions(filtername, filterargs)
         end
       end
@@ -79,26 +85,38 @@ module Liquid
       end
 
       obj = context.apply_global_filter(obj)
-
       taint_check(context, obj)
-
       obj
     end
 
+    def render_to_output_buffer(context, output)
+      obj = render(context)
+
+      if obj.is_a?(Array)
+        output << obj.join
+      elsif obj.nil?
+      else
+        output << obj.to_s
+      end
+
+      output
+    end
+
     private
 
     def parse_filter_expressions(filter_name, unparsed_args)
       filter_args = []
-      keyword_args = {}
+      keyword_args = nil
       unparsed_args.each do |a|
-        if matches = a.match(/\A#{TagAttributes}\z/o)
+        if matches = a.match(JustTagAttributes)
+          keyword_args ||= {}
           keyword_args[matches[1]] = Expression.parse(matches[2])
         else
           filter_args << Expression.parse(a)
         end
       end
       result = [filter_name, filter_args]
-      result << keyword_args unless keyword_args.empty?
+      result << keyword_args if keyword_args
       result
     end
 
@@ -132,5 +150,11 @@ module Liquid
         raise error
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.name] + @node.filters.flatten
+      end
+    end
   end
 end

lib/liquid/variable_lookup.rb

@@ -1,7 +1,7 @@
 module Liquid
   class VariableLookup
     SQUARE_BRACKETED = /\A\[(.*)\]\z/m
-    COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze]
+    COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze].freeze
 
     attr_reader :name, :lookups
 
@@ -78,5 +78,11 @@ module Liquid
     def state
       [@name, @lookups, @command_flags]
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.lookups
+      end
+    end
   end
 end

lib/liquid/version.rb

@@ -1,4 +1,5 @@
 # encoding: utf-8
+
 module Liquid
-  VERSION = "4.0.0"
+  VERSION = "4.0.3".freeze
 end

liquid.gemspec

@@ -1,4 +1,5 @@
 # encoding: utf-8
+
 lib = File.expand_path('../lib/', __FILE__)
 $LOAD_PATH.unshift lib unless $LOAD_PATH.include?(lib)
 
@@ -15,7 +16,7 @@ Gem::Specification.new do |s|
   s.license     = "MIT"
   # s.description = "A secure, non-evaling end user template engine with aesthetic markup."
 
-  s.required_ruby_version     = ">= 2.1.0"
+  s.required_ruby_version     = ">= 2.4.0"
   s.required_rubygems_version = ">= 1.3.7"
 
   s.test_files  = Dir.glob("{test}/**/*")

performance/benchmark.rb

@@ -5,7 +5,7 @@ Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 profiler = ThemeRunner.new
 
 Benchmark.ips do |x|
-  x.time = 60
+  x.time = 10
   x.warmup = 5
 
   puts
@@ -13,5 +13,6 @@ Benchmark.ips do |x|
   puts
 
   x.report("parse:") { profiler.compile }
-  x.report("parse & run:") { profiler.run }
+  x.report("render:") { profiler.render }
+  x.report("parse & render:") { profiler.run }
 end

performance/memory_profile.rb

@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'benchmark/ips'
+require 'memory_profiler'
+require 'terminal-table'
+require_relative 'theme_runner'
+
+class Profiler
+  LOG_LABEL   = "Profiling: ".rjust(14).freeze
+  REPORTS_DIR = File.expand_path('.memprof', __dir__).freeze
+
+  def self.run
+    puts
+    yield new
+  end
+
+  def initialize
+    @allocated = []
+    @retained  = []
+    @headings  = []
+  end
+
+  def profile(phase, &block)
+    print LOG_LABEL
+    print "#{phase}.. ".ljust(10)
+    report = MemoryProfiler.report(&block)
+    puts 'Done.'
+    @headings  << phase.capitalize
+    @allocated << "#{report.scale_bytes(report.total_allocated_memsize)} (#{report.total_allocated} objects)"
+    @retained  << "#{report.scale_bytes(report.total_retained_memsize)} (#{report.total_retained} objects)"
+
+    return if ENV['CI']
+
+    require 'fileutils'
+    report_file = File.join(REPORTS_DIR, "#{sanitize(phase)}.txt")
+    FileUtils.mkdir_p(REPORTS_DIR)
+    report.pretty_print(to_file: report_file, scale_bytes: true)
+  end
+
+  def tabulate
+    table = Terminal::Table.new(headings: @headings.unshift('Phase')) do |t|
+      t << @allocated.unshift('Total allocated')
+      t << @retained.unshift('Total retained')
+    end
+
+    puts
+    puts table
+    puts "\nDetailed report(s) saved to #{REPORTS_DIR}/" unless ENV['CI']
+  end
+
+  def sanitize(string)
+    string.downcase.gsub(/[\W]/, '-').squeeze('-')
+  end
+end
+
+Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
+
+runner = ThemeRunner.new
+Profiler.run do |x|
+  x.profile('parse') { runner.compile }
+  x.profile('render') { runner.render }
+  x.tabulate
+end

performance/shopify/comment_form.rb

@@ -12,7 +12,7 @@ class CommentForm < Liquid::Block
     end
   end
 
-  def render(context)
+  def render_to_output_buffer(context, output)
     article = context[@variable_name]
 
     context.stack do
@@ -23,7 +23,9 @@ class CommentForm < Liquid::Block
         'email'  => context['comment.email'],
         'body'   => context['comment.body']
       }
-      wrap_in_form(article, render_all(@nodelist, context))
+
+      output << wrap_in_form(article, render_all(@nodelist, context, output))
+      output
     end
   end
 

performance/shopify/paginate.rb

@@ -21,7 +21,7 @@ class Paginate < Liquid::Block
     end
   end
 
-  def render(context)
+  def render_to_output_buffer(context, output)
     @context = context
 
     context.stack do

performance/theme_runner.rb

@@ -21,53 +21,100 @@ class ThemeRunner
     end
   end
 
-  # Load all templates into memory, do this now so that
-  # we don't profile IO.
+  # Initialize a new liquid ThemeRunner instance
+  # Will load all templates into memory, do this now so that we don't profile IO.
   def initialize
     @tests = Dir[__dir__ + '/tests/**/*.liquid'].collect do |test|
       next if File.basename(test) == 'theme.liquid'
 
       theme_path = File.dirname(test) + '/theme.liquid'
-
-      [File.read(test), (File.file?(theme_path) ? File.read(theme_path) : nil), test]
+      {
+        liquid: File.read(test),
+        layout: (File.file?(theme_path) ? File.read(theme_path) : nil),
+        template_name: test
+      }
     end.compact
+
+    compile_all_tests
   end
 
+  # `compile` will test just the compilation portion of liquid without any templates
   def compile
-    # Dup assigns because will make some changes to them
-
-    @tests.each do |liquid, layout, template_name|
-      tmpl = Liquid::Template.new
-      tmpl.parse(liquid)
-      tmpl = Liquid::Template.new
-      tmpl.parse(layout)
+    @tests.each do |test_hash|
+      Liquid::Template.new.parse(test_hash[:liquid])
+      Liquid::Template.new.parse(test_hash[:layout])
     end
   end
 
+  # `run` is called to benchmark rendering and compiling at the same time
   def run
-    # Dup assigns because will make some changes to them
-    assigns = Database.tables.dup
-
-    @tests.each do |liquid, layout, template_name|
-      # Compute page_tempalte outside of profiler run, uninteresting to profiler
-      page_template = File.basename(template_name, File.extname(template_name))
+    each_test do |liquid, layout, assigns, page_template, template_name|
       compile_and_render(liquid, layout, assigns, page_template, template_name)
     end
   end
 
+  # `render` is called to benchmark just the render portion of liquid
+  def render
+    @compiled_tests.each do |test|
+      tmpl = test[:tmpl]
+      assigns = test[:assigns]
+      layout = test[:layout]
+
+      if layout
+        assigns['content_for_layout'] = tmpl.render!(assigns)
+        layout.render!(assigns)
+      else
+        tmpl.render!(assigns)
+      end
+    end
+  end
+
+  private
+
   def compile_and_render(template, layout, assigns, page_template, template_file)
+    compiled_test = compile_test(template, layout, assigns, page_template, template_file)
+    assigns['content_for_layout'] = compiled_test[:tmpl].render!(assigns)
+    compiled_test[:layout].render!(assigns) if layout
+  end
+
+  def compile_all_tests
+    @compiled_tests = []
+    each_test do |liquid, layout, assigns, page_template, template_name|
+      @compiled_tests << compile_test(liquid, layout, assigns, page_template, template_name)
+    end
+    @compiled_tests
+  end
+
+  def compile_test(template, layout, assigns, page_template, template_file)
+    tmpl = init_template(page_template, template_file)
+    parsed_template = tmpl.parse(template).dup
+
+    if layout
+      parsed_layout = tmpl.parse(layout)
+      { tmpl: parsed_template, assigns: assigns, layout: parsed_layout }
+    else
+      { tmpl: parsed_template, assigns: assigns }
+    end
+  end
+
+  # utility method with similar functionality needed in `compile_all_tests` and `run`
+  def each_test
+    # Dup assigns because will make some changes to them
+    assigns = Database.tables.dup
+
+    @tests.each do |test_hash|
+      # Compute page_template outside of profiler run, uninteresting to profiler
+      page_template = File.basename(test_hash[:template_name], File.extname(test_hash[:template_name]))
+      yield(test_hash[:liquid], test_hash[:layout], assigns, page_template, test_hash[:template_name])
+    end
+  end
+
+  # set up a new Liquid::Template object for use in `compile_and_render` and `compile_test`
+  def init_template(page_template, template_file)
     tmpl = Liquid::Template.new
     tmpl.assigns['page_title'] = 'Page title'
     tmpl.assigns['template'] = page_template
     tmpl.registers[:file_system] = ThemeRunner::FileSystem.new(File.dirname(template_file))
-
-    content_for_layout = tmpl.parse(template).render!(assigns)
-
-    if layout
-      assigns['content_for_layout'] = content_for_layout
-      tmpl.parse(layout).render!(assigns)
-    else
-      content_for_layout
-    end
+    tmpl
   end
 end

test/integration/blank_test.rb

@@ -1,11 +1,10 @@
 require 'test_helper'
 
 class FoobarTag < Liquid::Tag
-  def render(*args)
-    " "
+  def render_to_output_buffer(context, output)
+    output << ' '
+    output
   end
-
-  Liquid::Template.register_tag('foobar', FoobarTag)
 end
 
 class BlankTestFileSystem
@@ -31,7 +30,9 @@ class BlankTest < Minitest::Test
   end
 
   def test_new_tags_are_not_blank_by_default
-    assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
+    with_custom_tag('foobar', FoobarTag) do
+      assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
+    end
   end
 
   def test_loops_are_blank

test/integration/block_test.rb

@@ -0,0 +1,12 @@
+require 'test_helper'
+
+class BlockTest < Minitest::Test
+  include Liquid
+
+  def test_unexpected_end_tag
+    exc = assert_raises(SyntaxError) do
+      Template.parse("{% if true %}{% endunless %}")
+    end
+    assert_equal exc.message, "Liquid syntax error: 'endunless' is not a valid delimiter for if tags. use endif"
+  end
+end

test/integration/error_handling_test.rb

@@ -123,7 +123,7 @@ class ErrorHandlingTest < Minitest::Test
             ',
       error_mode: :warn,
       line_numbers: true
-                                     )
+    )
 
     assert_equal ['Liquid syntax error (line 4): Unexpected character = in "1 =! 2"'],
       template.warnings.map(&:message)
@@ -140,7 +140,7 @@ class ErrorHandlingTest < Minitest::Test
                 ',
         error_mode: :strict,
         line_numbers: true
-                            )
+      )
     end
 
     assert_equal 'Liquid syntax error (line 4): Unexpected character = in "1 =! 2"', err.message
@@ -158,7 +158,7 @@ class ErrorHandlingTest < Minitest::Test
           bla
                 ',
         line_numbers: true
-                            )
+      )
     end
 
     assert_equal "Liquid syntax error (line 5): Unknown tag 'foo'", err.message

test/integration/parse_tree_visitor_test.rb

@@ -0,0 +1,247 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ParseTreeVisitorTest < Minitest::Test
+  include Liquid
+
+  def test_variable
+    assert_equal(
+      ["test"],
+      visit(%({{ test }}))
+    )
+  end
+
+  def test_varible_with_filter
+    assert_equal(
+      ["test", "infilter"],
+      visit(%({{ test | split: infilter }}))
+    )
+  end
+
+  def test_dynamic_variable
+    assert_equal(
+      ["test", "inlookup"],
+      visit(%({{ test[inlookup] }}))
+    )
+  end
+
+  def test_if_condition
+    assert_equal(
+      ["test"],
+      visit(%({% if test %}{% endif %}))
+    )
+  end
+
+  def test_complex_if_condition
+    assert_equal(
+      ["test"],
+      visit(%({% if 1 == 1 and 2 == test %}{% endif %}))
+    )
+  end
+
+  def test_if_body
+    assert_equal(
+      ["test"],
+      visit(%({% if 1 == 1 %}{{ test }}{% endif %}))
+    )
+  end
+
+  def test_unless_condition
+    assert_equal(
+      ["test"],
+      visit(%({% unless test %}{% endunless %}))
+    )
+  end
+
+  def test_complex_unless_condition
+    assert_equal(
+      ["test"],
+      visit(%({% unless 1 == 1 and 2 == test %}{% endunless %}))
+    )
+  end
+
+  def test_unless_body
+    assert_equal(
+      ["test"],
+      visit(%({% unless 1 == 1 %}{{ test }}{% endunless %}))
+    )
+  end
+
+  def test_elsif_condition
+    assert_equal(
+      ["test"],
+      visit(%({% if 1 == 1 %}{% elsif test %}{% endif %}))
+    )
+  end
+
+  def test_complex_elsif_condition
+    assert_equal(
+      ["test"],
+      visit(%({% if 1 == 1 %}{% elsif 1 == 1 and 2 == test %}{% endif %}))
+    )
+  end
+
+  def test_elsif_body
+    assert_equal(
+      ["test"],
+      visit(%({% if 1 == 1 %}{% elsif 2 == 2 %}{{ test }}{% endif %}))
+    )
+  end
+
+  def test_else_body
+    assert_equal(
+      ["test"],
+      visit(%({% if 1 == 1 %}{% else %}{{ test }}{% endif %}))
+    )
+  end
+
+  def test_case_left
+    assert_equal(
+      ["test"],
+      visit(%({% case test %}{% endcase %}))
+    )
+  end
+
+  def test_case_condition
+    assert_equal(
+      ["test"],
+      visit(%({% case 1 %}{% when test %}{% endcase %}))
+    )
+  end
+
+  def test_case_when_body
+    assert_equal(
+      ["test"],
+      visit(%({% case 1 %}{% when 2 %}{{ test }}{% endcase %}))
+    )
+  end
+
+  def test_case_else_body
+    assert_equal(
+      ["test"],
+      visit(%({% case 1 %}{% else %}{{ test }}{% endcase %}))
+    )
+  end
+
+  def test_for_in
+    assert_equal(
+      ["test"],
+      visit(%({% for x in test %}{% endfor %}))
+    )
+  end
+
+  def test_for_limit
+    assert_equal(
+      ["test"],
+      visit(%({% for x in (1..5) limit: test %}{% endfor %}))
+    )
+  end
+
+  def test_for_offset
+    assert_equal(
+      ["test"],
+      visit(%({% for x in (1..5) offset: test %}{% endfor %}))
+    )
+  end
+
+  def test_for_body
+    assert_equal(
+      ["test"],
+      visit(%({% for x in (1..5) %}{{ test }}{% endfor %}))
+    )
+  end
+
+  def test_tablerow_in
+    assert_equal(
+      ["test"],
+      visit(%({% tablerow x in test %}{% endtablerow %}))
+    )
+  end
+
+  def test_tablerow_limit
+    assert_equal(
+      ["test"],
+      visit(%({% tablerow x in (1..5) limit: test %}{% endtablerow %}))
+    )
+  end
+
+  def test_tablerow_offset
+    assert_equal(
+      ["test"],
+      visit(%({% tablerow x in (1..5) offset: test %}{% endtablerow %}))
+    )
+  end
+
+  def test_tablerow_body
+    assert_equal(
+      ["test"],
+      visit(%({% tablerow x in (1..5) %}{{ test }}{% endtablerow %}))
+    )
+  end
+
+  def test_cycle
+    assert_equal(
+      ["test"],
+      visit(%({% cycle test %}))
+    )
+  end
+
+  def test_assign
+    assert_equal(
+      ["test"],
+      visit(%({% assign x = test %}))
+    )
+  end
+
+  def test_capture
+    assert_equal(
+      ["test"],
+      visit(%({% capture x %}{{ test }}{% endcapture %}))
+    )
+  end
+
+  def test_include
+    assert_equal(
+      ["test"],
+      visit(%({% include test %}))
+    )
+  end
+
+  def test_include_with
+    assert_equal(
+      ["test"],
+      visit(%({% include "hai" with test %}))
+    )
+  end
+
+  def test_include_for
+    assert_equal(
+      ["test"],
+      visit(%({% include "hai" for test %}))
+    )
+  end
+
+  def test_preserve_tree_structure
+    assert_equal(
+      [[nil, [
+        [nil, [[nil, [["other", []]]]]],
+        ["test", []],
+        ["xs", []]
+      ]]],
+      traversal(%({% for x in xs offset: test %}{{ other }}{% endfor %})).visit
+    )
+  end
+
+  private
+
+  def traversal(template)
+    ParseTreeVisitor
+      .for(Template.parse(template).root)
+      .add_callback_for(VariableLookup, &:name)
+  end
+
+  def visit(template)
+    traversal(template).visit.flatten.compact
+  end
+end

test/integration/parsing_quirks_test.rb

@@ -99,7 +99,7 @@ class ParsingQuirksTest < Minitest::Test
       # After the messed up quotes a filter without parameters (reverse) should work
       # but one with parameters (remove) shouldn't be detected.
       assert_template_result('here',  "{{ 'hi there' | split:\"t\"\" | reverse | first}}")
-      assert_template_result('hi ',  "{{ 'hi there' | split:\"t\"\" | remove:\"i\" | first}}")
+      assert_template_result('hi ', "{{ 'hi there' | split:\"t\"\" | remove:\"i\" | first}}")
     end
   end
 
@@ -115,4 +115,8 @@ class ParsingQuirksTest < Minitest::Test
       assert_template_result('12345', "{% for i in (1...5) %}{{ i }}{% endfor %}")
     end
   end
+
+  def test_contains_in_id
+    assert_template_result(' YES ', '{% if containsallshipments == true %} YES {% endif %}', 'containsallshipments' => true)
+  end
 end # ParsingQuirksTest

test/integration/security_test.rb

@@ -63,4 +63,18 @@ class SecurityTest < Minitest::Test
 
     assert_equal [], (Symbol.all_symbols - current_symbols)
   end
+
+  def test_max_depth_nested_blocks_does_not_raise_exception
+    depth = Liquid::Block::MAX_DEPTH
+    code = "{% if true %}" * depth + "rendered" + "{% endif %}" * depth
+    assert_equal "rendered", Template.parse(code).render!
+  end
+
+  def test_more_than_max_depth_nested_blocks_raises_exception
+    depth = Liquid::Block::MAX_DEPTH + 1
+    code = "{% if true %}" * depth + "rendered" + "{% endif %}" * depth
+    assert_raises(Liquid::StackLevelError) do
+      Template.parse(code).render!
+    end
+  end
 end # SecurityTest

test/integration/standard_filter_test.rb

@@ -128,8 +128,16 @@ class StandardFiltersTest < Minitest::Test
 
   def test_escape
     assert_equal '&lt;strong&gt;', @filters.escape('<strong>')
-    assert_equal nil, @filters.escape(nil)
+    assert_equal '1', @filters.escape(1)
+    assert_equal '2001-02-03', @filters.escape(Date.new(2001, 2, 3))
+    assert_nil @filters.escape(nil)
+  end
+
+  def test_h
     assert_equal '&lt;strong&gt;', @filters.h('<strong>')
+    assert_equal '1', @filters.h(1)
+    assert_equal '2001-02-03', @filters.h(Date.new(2001, 2, 3))
+    assert_nil @filters.h(nil)
   end
 
   def test_escape_once
@@ -138,14 +146,22 @@ class StandardFiltersTest < Minitest::Test
 
   def test_url_encode
     assert_equal 'foo%2B1%40example.com', @filters.url_encode('foo+1@example.com')
-    assert_equal nil, @filters.url_encode(nil)
+    assert_equal '1', @filters.url_encode(1)
+    assert_equal '2001-02-03', @filters.url_encode(Date.new(2001, 2, 3))
+    assert_nil @filters.url_encode(nil)
   end
 
   def test_url_decode
     assert_equal 'foo bar', @filters.url_decode('foo+bar')
     assert_equal 'foo bar', @filters.url_decode('foo%20bar')
     assert_equal 'foo+1@example.com', @filters.url_decode('foo%2B1%40example.com')
-    assert_equal nil, @filters.url_decode(nil)
+    assert_equal '1', @filters.url_decode(1)
+    assert_equal '2001-02-03', @filters.url_decode(Date.new(2001, 2, 3))
+    assert_nil @filters.url_decode(nil)
+    exception = assert_raises Liquid::ArgumentError do
+      @filters.url_decode('%ff')
+    end
+    assert_equal 'Liquid error: invalid byte sequence in UTF-8', exception.message
   end
 
   def test_truncatewords
@@ -165,11 +181,15 @@ class StandardFiltersTest < Minitest::Test
     assert_equal 'test', @filters.strip_html("<div\nclass='multiline'>test</div>")
     assert_equal 'test', @filters.strip_html("<!-- foo bar \n test -->test")
     assert_equal '', @filters.strip_html(nil)
+
+    # Quirk of the existing implementation
+    assert_equal 'foo;', @filters.strip_html("<<<script </script>script>foo;</script>")
   end
 
   def test_join
     assert_equal '1 2 3 4', @filters.join([1, 2, 3, 4])
     assert_equal '1 - 2 - 3 - 4', @filters.join([1, 2, 3, 4], ' - ')
+    assert_equal '1121314', @filters.join([1, 2, 3, 4], 1)
   end
 
   def test_sort
@@ -177,6 +197,11 @@ class StandardFiltersTest < Minitest::Test
     assert_equal [{ "a" => 1 }, { "a" => 2 }, { "a" => 3 }, { "a" => 4 }], @filters.sort([{ "a" => 4 }, { "a" => 3 }, { "a" => 1 }, { "a" => 2 }], "a")
   end
 
+  def test_sort_with_nils
+    assert_equal [1, 2, 3, 4, nil], @filters.sort([nil, 4, 3, 2, 1])
+    assert_equal [{ "a" => 1 }, { "a" => 2 }, { "a" => 3 }, { "a" => 4 }, {}], @filters.sort([{ "a" => 4 }, { "a" => 3 }, {}, { "a" => 1 }, { "a" => 2 }], "a")
+  end
+
   def test_sort_when_property_is_sometimes_missing_puts_nils_last
     input = [
       { "price" => 4, "handle" => "alpha" },
@@ -195,14 +220,89 @@ class StandardFiltersTest < Minitest::Test
     assert_equal expectation, @filters.sort(input, "price")
   end
 
+  def test_sort_natural
+    assert_equal ["a", "B", "c", "D"], @filters.sort_natural(["c", "D", "a", "B"])
+    assert_equal [{ "a" => "a" }, { "a" => "B" }, { "a" => "c" }, { "a" => "D" }], @filters.sort_natural([{ "a" => "D" }, { "a" => "c" }, { "a" => "a" }, { "a" => "B" }], "a")
+  end
+
+  def test_sort_natural_with_nils
+    assert_equal ["a", "B", "c", "D", nil], @filters.sort_natural([nil, "c", "D", "a", "B"])
+    assert_equal [{ "a" => "a" }, { "a" => "B" }, { "a" => "c" }, { "a" => "D" }, {}], @filters.sort_natural([{ "a" => "D" }, { "a" => "c" }, {}, { "a" => "a" }, { "a" => "B" }], "a")
+  end
+
+  def test_sort_natural_when_property_is_sometimes_missing_puts_nils_last
+    input = [
+      { "price" => "4", "handle" => "alpha" },
+      { "handle" => "beta" },
+      { "price" => "1", "handle" => "gamma" },
+      { "handle" => "delta" },
+      { "price" => 2, "handle" => "epsilon" }
+    ]
+    expectation = [
+      { "price" => "1", "handle" => "gamma" },
+      { "price" => 2, "handle" => "epsilon" },
+      { "price" => "4", "handle" => "alpha" },
+      { "handle" => "delta" },
+      { "handle" => "beta" }
+    ]
+    assert_equal expectation, @filters.sort_natural(input, "price")
+  end
+
+  def test_sort_natural_case_check
+    input = [
+      { "key" => "X" },
+      { "key" => "Y" },
+      { "key" => "Z" },
+      { "fake" => "t" },
+      { "key" => "a" },
+      { "key" => "b" },
+      { "key" => "c" }
+    ]
+    expectation = [
+      { "key" => "a" },
+      { "key" => "b" },
+      { "key" => "c" },
+      { "key" => "X" },
+      { "key" => "Y" },
+      { "key" => "Z" },
+      { "fake" => "t" }
+    ]
+    assert_equal expectation, @filters.sort_natural(input, "key")
+    assert_equal ["a", "b", "c", "X", "Y", "Z"], @filters.sort_natural(["X", "Y", "Z", "a", "b", "c"])
+  end
+
   def test_sort_empty_array
     assert_equal [], @filters.sort([], "a")
   end
 
+  def test_sort_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3]
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.sort(foo, "bar")
+    end
+  end
+
   def test_sort_natural_empty_array
     assert_equal [], @filters.sort_natural([], "a")
   end
 
+  def test_sort_natural_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3]
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.sort_natural(foo, "bar")
+    end
+  end
+
   def test_legacy_sort_hash
     assert_equal [{ a: 1, b: 2 }], @filters.sort({ a: 1, b: 2 })
   end
@@ -226,10 +326,34 @@ class StandardFiltersTest < Minitest::Test
     assert_equal [], @filters.uniq([], "a")
   end
 
+  def test_uniq_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3]
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.uniq(foo, "bar")
+    end
+  end
+
   def test_compact_empty_array
     assert_equal [], @filters.compact([], "a")
   end
 
+  def test_compact_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3]
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.compact(foo, "bar")
+    end
+  end
+
   def test_reverse
     assert_equal [4, 3, 2, 1], @filters.reverse([1, 2, 3, 4])
   end
@@ -295,6 +419,29 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result "123", '{{ foo | map: "foo" }}', "foo" => TestEnumerable.new
   end
 
+  def test_map_returns_empty_on_2d_input_array
+    foo = [
+      [1],
+      [2],
+      [3]
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.map(foo, "bar")
+    end
+  end
+
+  def test_map_returns_empty_with_no_property
+    foo = [
+      [1],
+      [2],
+      [3]
+    ]
+    assert_raises Liquid::ArgumentError do
+      @filters.map(foo, nil)
+    end
+  end
+
   def test_sort_works_on_enumerables
     assert_template_result "213", '{{ foo | sort: "bar" | map: "foo" }}', "foo" => TestEnumerable.new
   end
@@ -325,11 +472,11 @@ class StandardFiltersTest < Minitest::Test
     assert_equal '07/05/2006', @filters.date("2006-07-05 10:00:00", "%m/%d/%Y")
 
     assert_equal "07/16/2004", @filters.date("Fri Jul 16 01:00:00 2004", "%m/%d/%Y")
-    assert_equal "#{Date.today.year}", @filters.date('now', '%Y')
-    assert_equal "#{Date.today.year}", @filters.date('today', '%Y')
-    assert_equal "#{Date.today.year}", @filters.date('Today', '%Y')
+    assert_equal Date.today.year.to_s, @filters.date('now', '%Y')
+    assert_equal Date.today.year.to_s, @filters.date('today', '%Y')
+    assert_equal Date.today.year.to_s, @filters.date('Today', '%Y')
 
-    assert_equal nil, @filters.date(nil, "%B")
+    assert_nil @filters.date(nil, "%B")
 
     assert_equal '', @filters.date('', "%B")
 
@@ -342,8 +489,8 @@ class StandardFiltersTest < Minitest::Test
   def test_first_last
     assert_equal 1, @filters.first([1, 2, 3])
     assert_equal 3, @filters.last([1, 2, 3])
-    assert_equal nil, @filters.first([])
-    assert_equal nil, @filters.last([])
+    assert_nil @filters.first([])
+    assert_nil @filters.last([])
   end
 
   def test_replace
@@ -483,6 +630,28 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result "5", "{{ price | floor }}", 'price' => NumberLikeThing.new(5.4)
   end
 
+  def test_at_most
+    assert_template_result "4", "{{ 5 | at_most:4 }}"
+    assert_template_result "5", "{{ 5 | at_most:5 }}"
+    assert_template_result "5", "{{ 5 | at_most:6 }}"
+
+    assert_template_result "4.5", "{{ 4.5 | at_most:5 }}"
+    assert_template_result "5", "{{ width | at_most:5 }}", 'width' => NumberLikeThing.new(6)
+    assert_template_result "4", "{{ width | at_most:5 }}", 'width' => NumberLikeThing.new(4)
+    assert_template_result "4", "{{ 5 | at_most: width }}", 'width' => NumberLikeThing.new(4)
+  end
+
+  def test_at_least
+    assert_template_result "5", "{{ 5 | at_least:4 }}"
+    assert_template_result "5", "{{ 5 | at_least:5 }}"
+    assert_template_result "6", "{{ 5 | at_least:6 }}"
+
+    assert_template_result "5", "{{ 4.5 | at_least:5 }}"
+    assert_template_result "6", "{{ width | at_least:5 }}", 'width' => NumberLikeThing.new(6)
+    assert_template_result "5", "{{ width | at_least:5 }}", 'width' => NumberLikeThing.new(4)
+    assert_template_result "6", "{{ 5 | at_least: width }}", 'width' => NumberLikeThing.new(6)
+  end
+
   def test_append
     assigns = { 'a' => 'bc', 'b' => 'd' }
     assert_template_result('bcd', "{{ a | append: 'd'}}", assigns)
@@ -523,6 +692,78 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result('abc', "{{ 'abc' | date: '%D' }}")
   end
 
+  def test_where
+    input = [
+      { "handle" => "alpha", "ok" => true },
+      { "handle" => "beta", "ok" => false },
+      { "handle" => "gamma", "ok" => false },
+      { "handle" => "delta", "ok" => true }
+    ]
+
+    expectation = [
+      { "handle" => "alpha", "ok" => true },
+      { "handle" => "delta", "ok" => true }
+    ]
+
+    assert_equal expectation, @filters.where(input, "ok", true)
+    assert_equal expectation, @filters.where(input, "ok")
+  end
+
+  def test_where_no_key_set
+    input = [
+      { "handle" => "alpha", "ok" => true },
+      { "handle" => "beta" },
+      { "handle" => "gamma" },
+      { "handle" => "delta", "ok" => true }
+    ]
+
+    expectation = [
+      { "handle" => "alpha", "ok" => true },
+      { "handle" => "delta", "ok" => true }
+    ]
+
+    assert_equal expectation, @filters.where(input, "ok", true)
+    assert_equal expectation, @filters.where(input, "ok")
+  end
+
+  def test_where_non_array_map_input
+    assert_equal [{ "a" => "ok" }], @filters.where({ "a" => "ok" }, "a", "ok")
+    assert_equal [], @filters.where({ "a" => "not ok" }, "a", "ok")
+  end
+
+  def test_where_indexable_but_non_map_value
+    assert_raises(Liquid::ArgumentError) { @filters.where(1, "ok", true) }
+    assert_raises(Liquid::ArgumentError) { @filters.where(1, "ok") }
+  end
+
+  def test_where_non_boolean_value
+    input = [
+      { "message" => "Bonjour!", "language" => "French" },
+      { "message" => "Hello!", "language" => "English" },
+      { "message" => "Hallo!", "language" => "German" }
+    ]
+
+    assert_equal [{ "message" => "Bonjour!", "language" => "French" }], @filters.where(input, "language", "French")
+    assert_equal [{ "message" => "Hallo!", "language" => "German" }], @filters.where(input, "language", "German")
+    assert_equal [{ "message" => "Hello!", "language" => "English" }], @filters.where(input, "language", "English")
+  end
+
+  def test_where_array_of_only_unindexable_values
+    assert_nil @filters.where([nil], "ok", true)
+    assert_nil @filters.where([nil], "ok")
+  end
+
+  def test_where_no_target_value
+    input = [
+      { "foo" => false },
+      { "foo" => true },
+      { "foo" => "for sure" },
+      { "bar" => true }
+    ]
+
+    assert_equal [{ "foo" => true }, { "foo" => "for sure" }], @filters.where(input, "foo")
+  end
+
   private
 
   def with_timezone(tz)

test/integration/tags/echo_test.rb

@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class EchoTest < Minitest::Test
+  include Liquid
+
+  def test_echo_outputs_its_input
+    assert_template_result('BAR', <<~LIQUID, { 'variable-name' => 'bar' })
+      {%- echo variable-name | upcase -%}
+    LIQUID
+  end
+end

test/integration/tags/for_tag_test.rb

@@ -103,6 +103,34 @@ HERE
     assert_template_result('3456', '{%for i in array limit: 4 offset: 2 %}{{ i }}{%endfor%}', assigns)
   end
 
+  def test_limiting_with_invalid_limit
+    assigns = { 'array' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] }
+    template = <<-MKUP
+      {% for i in array limit: true offset: 1 %}
+        {{ i }}
+      {% endfor %}
+    MKUP
+
+    exception = assert_raises(Liquid::ArgumentError) do
+      Template.parse(template).render!(assigns)
+    end
+    assert_equal("Liquid error: invalid integer", exception.message)
+  end
+
+  def test_limiting_with_invalid_offset
+    assigns = { 'array' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] }
+    template = <<-MKUP
+      {% for i in array limit: 1 offset: true %}
+        {{ i }}
+      {% endfor %}
+    MKUP
+
+    exception = assert_raises(Liquid::ArgumentError) do
+      Template.parse(template).render!(assigns)
+    end
+    assert_equal("Liquid error: invalid integer", exception.message)
+  end
+
   def test_dynamic_variable_limiting
     assigns = { 'array' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] }
     assigns['limit'] = 2
@@ -159,7 +187,7 @@ HERE
     assert_template_result(expected, markup, assigns)
   end
 
-  def test_pause_resume_BIG_limit
+  def test_pause_resume_big_limit
     assigns = { 'array' => { 'items' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] } }
     markup = <<-MKUP
       {%for i in array.items limit:3 %}{{i}}{%endfor%}
@@ -178,7 +206,7 @@ HERE
     assert_template_result(expected, markup, assigns)
   end
 
-  def test_pause_resume_BIG_offset
+  def test_pause_resume_big_offset
     assigns = { 'array' => { 'items' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] } }
     markup = '{%for i in array.items limit:3 %}{{i}}{%endfor%}
       next

test/integration/tags/include_tag_test.rb

@@ -30,6 +30,9 @@ class TestFileSystem
     when 'assignments'
       "{% assign foo = 'bar' %}"
 
+    when 'break'
+      "{% break %}"
+
     else
       template_path
     end
@@ -63,8 +66,9 @@ class CustomInclude < Liquid::Tag
   def parse(tokens)
   end
 
-  def render(context)
-    @template_name[1..-2]
+  def render_to_output_buffer(context, output)
+    output << @template_name[1..-2]
+    output
   end
 end
 
@@ -137,7 +141,7 @@ class IncludeTagTest < Minitest::Test
 
     Liquid::Template.file_system = infinite_file_system.new
 
-    assert_raises(Liquid::StackLevelError, SystemStackError) do
+    assert_raises(Liquid::StackLevelError) do
       Template.parse("{% include 'loop' %}").render!
     end
   end
@@ -235,4 +239,16 @@ class IncludeTagTest < Minitest::Test
 
     assert_template_result "Product: Draft 151cm ", "{% assign page = 'product' %}{% include page for foo %}", "foo" => { 'title' => 'Draft 151cm' }
   end
+
+  def test_including_with_strict_variables
+    template = Liquid::Template.parse("{% include 'simple' %}", error_mode: :warn)
+    template.render(nil, strict_variables: true)
+
+    assert_equal [], template.errors
+  end
+
+  def test_break_through_include
+    assert_template_result "1", "{% for i in (1..3) %}{{ i }}{% break %}{{ i }}{% endfor %}"
+    assert_template_result "1", "{% for i in (1..3) %}{{ i }}{% include 'break' %}{{ i }}{% endfor %}"
+  end
 end # IncludeTagTest

test/integration/tags/liquid_tag_test.rb

@@ -0,0 +1,104 @@
+require 'test_helper'
+
+class LiquidTagTest < Minitest::Test
+  include Liquid
+
+  def test_liquid_tag
+    assert_template_result('1 2 3', <<~LIQUID, 'array' => [1, 2, 3])
+      {%- liquid
+        echo array | join: " "
+      -%}
+    LIQUID
+
+    assert_template_result('1 2 3', <<~LIQUID, 'array' => [1, 2, 3])
+      {%- liquid
+        for value in array
+          echo value
+          unless forloop.last
+            echo " "
+          endunless
+        endfor
+      -%}
+    LIQUID
+
+    assert_template_result('4 8 12 6', <<~LIQUID, 'array' => [1, 2, 3])
+      {%- liquid
+        for value in array
+          assign double_value = value | times: 2
+          echo double_value | times: 2
+          unless forloop.last
+            echo " "
+          endunless
+        endfor
+
+        echo " "
+        echo double_value
+      -%}
+    LIQUID
+
+    assert_template_result('abc', <<~LIQUID)
+      {%- liquid echo "a" -%}
+      b
+      {%- liquid echo "c" -%}
+    LIQUID
+  end
+
+  def test_liquid_tag_errors
+    assert_match_syntax_error("syntax error (line 1): Unknown tag 'error'", <<~LIQUID)
+      {%- liquid error no such tag -%}
+    LIQUID
+
+    assert_match_syntax_error("syntax error (line 7): Unknown tag 'error'", <<~LIQUID)
+      {{ test }}
+
+      {%-
+      liquid
+        for value in array
+
+          error no such tag
+        endfor
+      -%}
+    LIQUID
+
+    assert_match_syntax_error("syntax error (line 2): Unknown tag '!!! the guards are vigilant'", <<~LIQUID)
+      {%- liquid
+        !!! the guards are vigilant
+      -%}
+    LIQUID
+
+    assert_match_syntax_error("syntax error (line 4): 'for' tag was never closed", <<~LIQUID)
+      {%- liquid
+        for value in array
+          echo 'forgot to close the for tag'
+      -%}
+    LIQUID
+  end
+
+  def test_line_number_is_correct_after_a_blank_token
+    assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n\n error %}")
+    assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n  \n error %}")
+  end
+
+  def test_cannot_open_blocks_living_past_a_liquid_tag
+    assert_match_syntax_error("syntax error (line 3): 'if' tag was never closed", <<~LIQUID)
+      {%- liquid
+        if true
+      -%}
+      {%- endif -%}
+    LIQUID
+  end
+
+  def test_quirk_can_close_blocks_created_before_a_liquid_tag
+    assert_template_result("42", <<~LIQUID)
+      {%- if true -%}
+      42
+      {%- liquid endif -%}
+    LIQUID
+  end
+
+  def test_liquid_tag_in_raw
+    assert_template_result("{% liquid echo 'test' %}\n", <<~LIQUID)
+      {% raw %}{% liquid echo 'test' %}{% endraw %}
+    LIQUID
+  end
+end

test/integration/tags/render_tag_test.rb

@@ -0,0 +1,149 @@
+require 'test_helper'
+
+class RenderTagTest < Minitest::Test
+  include Liquid
+
+  def test_render_with_no_arguments
+    Liquid::Template.file_system = StubFileSystem.new('source' => 'rendered content')
+    assert_template_result 'rendered content', '{% render "source" %}'
+  end
+
+  def test_render_tag_looks_for_file_system_in_registers_first
+    file_system = StubFileSystem.new('pick_a_source' => 'from register file system')
+    assert_equal 'from register file system',
+      Template.parse('{% render "pick_a_source" %}').render!({}, registers: { file_system: file_system })
+  end
+
+  def test_render_passes_named_arguments_into_inner_scope
+    Liquid::Template.file_system = StubFileSystem.new('product' => '{{ inner_product.title }}')
+    assert_template_result 'My Product', '{% render "product", inner_product: outer_product %}',
+      'outer_product' => { 'title' => 'My Product' }
+  end
+
+  def test_render_accepts_literals_as_arguments
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ price }}')
+    assert_template_result '123', '{% render "snippet", price: 123 %}'
+  end
+
+  def test_render_accepts_multiple_named_arguments
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ one }} {{ two }}')
+    assert_template_result '1 2', '{% render "snippet", one: 1, two: 2 %}'
+  end
+
+  def test_render_does_not_inherit_parent_scope_variables
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ outer_variable }}')
+    assert_template_result '', '{% assign outer_variable = "should not be visible" %}{% render "snippet" %}'
+  end
+
+  def test_render_does_not_inherit_variable_with_same_name_as_snippet
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ snippet }}')
+    assert_template_result '', "{% assign snippet = 'should not be visible' %}{% render 'snippet' %}"
+  end
+
+  def test_render_sets_the_correct_template_name_for_errors
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ unsafe }}')
+
+    with_taint_mode :error do
+      template = Liquid::Template.parse('{% render "snippet", unsafe: unsafe %}')
+      context = Context.new('unsafe' => (+'unsafe').tap(&:taint))
+      template.render(context)
+
+      assert_equal [Liquid::TaintedError], template.errors.map(&:class)
+      assert_equal 'snippet', template.errors.first.template_name
+    end
+  end
+
+  def test_render_sets_the_correct_template_name_for_warnings
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ unsafe }}')
+
+    with_taint_mode :warn do
+      template = Liquid::Template.parse('{% render "snippet", unsafe: unsafe %}')
+      context = Context.new('unsafe' => (+'unsafe').tap(&:taint))
+      template.render(context)
+
+      assert_equal [Liquid::TaintedError], context.warnings.map(&:class)
+      assert_equal 'snippet', context.warnings.first.template_name
+    end
+  end
+
+  def test_render_does_not_mutate_parent_scope
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{% assign inner = 1 %}')
+    assert_template_result '', "{% render 'snippet' %}{{ inner }}"
+  end
+
+  def test_nested_render_tag
+    Liquid::Template.file_system = StubFileSystem.new(
+      'one' => "one {% render 'two' %}",
+      'two' => 'two'
+    )
+    assert_template_result 'one two', "{% render 'one' %}"
+  end
+
+  def test_recursively_rendered_template_does_not_produce_endless_loop
+    Liquid::Template.file_system = StubFileSystem.new('loop' => '{% render "loop" %}')
+
+    assert_raises Liquid::StackLevelError do
+      Template.parse('{% render "loop" %}').render!
+    end
+  end
+
+  def test_includes_and_renders_count_towards_the_same_recursion_limit
+    Liquid::Template.file_system = StubFileSystem.new(
+      'loop_render' => '{% render "loop_include" %}',
+      'loop_include' => '{% include "loop_render" %}'
+    )
+
+    assert_raises Liquid::StackLevelError  do
+      Template.parse('{% render "loop_include" %}').render!
+    end
+  end
+
+  def test_dynamically_choosen_templates_are_not_allowed
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => 'should not be rendered')
+
+    assert_raises Liquid::SyntaxError do
+      Liquid::Template.parse("{% assign name = 'snippet' %}{% render name %}")
+    end
+  end
+
+  def test_include_tag_caches_second_read_of_same_partial
+    file_system = StubFileSystem.new('snippet' => 'echo')
+    assert_equal 'echoecho',
+      Template.parse('{% render "snippet" %}{% render "snippet" %}')
+              .render!({}, registers: { file_system: file_system })
+    assert_equal 1, file_system.file_read_count
+  end
+
+  def test_render_tag_doesnt_cache_partials_across_renders
+    file_system = StubFileSystem.new('snippet' => 'my message')
+
+    assert_equal 'my message',
+      Template.parse('{% include "snippet" %}').render!({}, registers: { file_system: file_system })
+    assert_equal 1, file_system.file_read_count
+
+    assert_equal 'my message',
+      Template.parse('{% include "snippet" %}').render!({}, registers: { file_system: file_system })
+    assert_equal 2, file_system.file_read_count
+  end
+
+  def test_render_tag_within_if_statement
+    Liquid::Template.file_system = StubFileSystem.new('snippet' => 'my message')
+    assert_template_result 'my message', '{% if true %}{% render "snippet" %}{% endif %}'
+  end
+
+  def test_break_through_render
+    Liquid::Template.file_system = StubFileSystem.new('break' => '{% break %}')
+    assert_template_result '1', '{% for i in (1..3) %}{{ i }}{% break %}{{ i }}{% endfor %}'
+    assert_template_result '112233', '{% for i in (1..3) %}{{ i }}{% render "break" %}{{ i }}{% endfor %}'
+  end
+
+  def test_increment_is_isolated_between_renders
+    Liquid::Template.file_system = StubFileSystem.new('incr' => '{% increment %}')
+    assert_template_result '010', '{% increment %}{% increment %}{% render "incr" %}'
+  end
+
+  def test_decrement_is_isolated_between_renders
+    Liquid::Template.file_system = StubFileSystem.new('decr' => '{% decrement %}')
+    assert_template_result '-1-2-1', '{% decrement %}{% decrement %}{% render "decr" %}'
+  end
+end

test/integration/template_test.rb

@@ -139,6 +139,16 @@ class TemplateTest < Minitest::Test
     refute_nil t.resource_limits.assign_score
   end
 
+  def test_resource_limits_assign_score_counts_bytes_not_characters
+    t = Template.parse("{% assign foo = 'すごい' %}")
+    t.render
+    assert_equal 9, t.resource_limits.assign_score
+
+    t = Template.parse("{% capture foo %}すごい{% endcapture %}")
+    t.render
+    assert_equal 9, t.resource_limits.assign_score
+  end
+
   def test_resource_limits_assign_score_nested
     t = Template.parse("{% assign foo = 'aaaa' | reverse %}")
 
@@ -187,6 +197,14 @@ class TemplateTest < Minitest::Test
     assert_equal "ababab", t.render
   end
 
+  def test_render_length_uses_number_of_bytes_not_characters
+    t = Template.parse("{% if true %}すごい{% endif %}")
+    t.resource_limits.render_length_limit = 10
+    assert_equal "Liquid error: Memory limits exceeded", t.render
+    t.resource_limits.render_length_limit = 18
+    assert_equal "すごい", t.render
+  end
+
   def test_default_resource_limits_unaffected_by_render_with_context
     context = Context.new
     t = Template.parse("{% for a in (1..100) %} {% assign foo = 1 %} {% endfor %}")
@@ -261,6 +279,15 @@ class TemplateTest < Minitest::Test
     assert_equal 'Liquid error: undefined variable d', t.errors[2].message
   end
 
+  def test_nil_value_does_not_raise
+    Liquid::Template.error_mode = :strict
+    t = Template.parse("some{{x}}thing")
+    result = t.render!({ 'x' => nil }, strict_variables: true)
+
+    assert_equal 0, t.errors.count
+    assert_equal 'something', result
+  end
+
   def test_undefined_variables_raise
     t = Template.parse("{{x}} {{y}} {{z.a}} {{z.b}} {{z.c.d}}")
 

test/integration/trim_mode_test.rb

@@ -496,6 +496,10 @@ class TrimModeTest < Minitest::Test
     assert_template_result(expected, text)
   end
 
+  def test_right_trim_followed_by_tag
+    assert_template_result('ab c', '{{ "a" -}}{{ "b" }} c')
+  end
+
   def test_raw_output
     whitespace = '        '
     text = <<-END_TEMPLATE

test/integration/variable_test.rb

@@ -89,4 +89,8 @@ class VariableTest < Minitest::Test
   def test_multiline_variable
     assert_equal 'worked', Template.parse("{{\ntest\n}}").render!('test' => 'worked')
   end
+
+  def test_render_symbol
+    assert_template_result 'bar', '{{ foo }}', 'foo' => :bar
+  end
 end

test/test_helper.rb

@@ -2,7 +2,6 @@
 
 ENV["MT_NO_EXPECTATIONS"] = "1"
 require 'minitest/autorun'
-require 'spy/integration'
 
 $LOAD_PATH.unshift(File.join(File.expand_path(__dir__), '..', 'lib'))
 require 'liquid.rb'
@@ -15,7 +14,7 @@ if env_mode = ENV['LIQUID_PARSER_MODE']
 end
 Liquid::Template.error_mode = mode
 
-if ENV['LIQUID-C'] == '1'
+if ENV['LIQUID_C'] == '1'
   puts "-- LIQUID C"
   require 'liquid/c'
 end
@@ -38,18 +37,18 @@ module Minitest
     include Liquid
 
     def assert_template_result(expected, template, assigns = {}, message = nil)
-      assert_equal expected, Template.parse(template).render!(assigns), message
+      assert_equal expected, Template.parse(template, line_numbers: true).render!(assigns), message
     end
 
     def assert_template_result_matches(expected, template, assigns = {}, message = nil)
       return assert_template_result(expected, template, assigns, message) unless expected.is_a? Regexp
 
-      assert_match expected, Template.parse(template).render!(assigns), message
+      assert_match expected, Template.parse(template, line_numbers: true).render!(assigns), message
     end
 
     def assert_match_syntax_error(match, template, assigns = {})
       exception = assert_raises(Liquid::SyntaxError) do
-        Template.parse(template).render(assigns)
+        Template.parse(template, line_numbers: true).render(assigns)
       end
       assert_match match, exception.message
     end
@@ -85,6 +84,13 @@ module Minitest
     ensure
       Liquid::Template.error_mode = old_mode
     end
+
+    def with_custom_tag(tag_name, tag_class)
+      Liquid::Template.register_tag(tag_name, tag_class)
+      yield
+    ensure
+      Liquid::Template.tags.delete(tag_name)
+    end
   end
 end
 
@@ -115,3 +121,17 @@ class ErrorDrop < Liquid::Drop
     raise Exception, 'exception'
   end
 end
+
+class StubFileSystem
+  attr_reader :file_read_count
+
+  def initialize(values)
+    @file_read_count = 0
+    @values = values
+  end
+
+  def read_template_file(template_path)
+    @file_read_count += 1
+    @values.fetch(template_path)
+  end
+end

test/unit/block_unit_test.rb

@@ -44,10 +44,47 @@ class BlockUnitTest < Minitest::Test
   end
 
   def test_with_custom_tag
-    Liquid::Template.register_tag("testtag", Block)
-    assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
-  ensure
-    Liquid::Template.tags.delete('testtag')
+    with_custom_tag('testtag', Block) do
+      assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
+    end
+  end
+
+  def test_custom_block_tags_have_a_default_render_to_output_buffer_method_for_backwards_compatibility
+    klass1 = Class.new(Block) do
+      def render(*)
+        'hello'
+      end
+    end
+
+    with_custom_tag('blabla', klass1) do
+      template = Liquid::Template.parse("{% blabla %} bla {% endblabla %}")
+
+      assert_equal 'hello', template.render
+
+      buf = ''
+      output = template.render({}, output: buf)
+      assert_equal 'hello', output
+      assert_equal 'hello', buf
+      assert_equal buf.object_id, output.object_id
+    end
+
+    klass2 = Class.new(klass1) do
+      def render(*)
+        'foo' + super + 'bar'
+      end
+    end
+
+    with_custom_tag('blabla', klass2) do
+      template = Liquid::Template.parse("{% blabla %} foo {% endblabla %}")
+
+      assert_equal 'foohellobar', template.render
+
+      buf = ''
+      output = template.render({}, output: buf)
+      assert_equal 'foohellobar', output
+      assert_equal 'foohellobar', buf
+      assert_equal buf.object_id, output.object_id
+    end
   end
 
   private

test/unit/condition_unit_test.rb

@@ -24,9 +24,9 @@ class ConditionUnitTest < Minitest::Test
     assert_evaluates_true 1, '<=', 1
     # negative numbers
     assert_evaluates_true 1, '>', -1
-    assert_evaluates_true (-1), '<', 1
+    assert_evaluates_true -1, '<', 1
     assert_evaluates_true 1.0, '>', -1.0
-    assert_evaluates_true (-1.0), '<', 1.0
+    assert_evaluates_true -1.0, '<', 1.0
   end
 
   def test_default_operators_evalute_false
@@ -64,6 +64,14 @@ class ConditionUnitTest < Minitest::Test
     assert_evaluates_argument_error '1', '<=', 0
   end
 
+  def test_hash_compare_backwards_compatibility
+    assert_nil Condition.new({}, '>', 2).evaluate
+    assert_nil Condition.new(2, '>', {}).evaluate
+    assert_equal false, Condition.new({}, '==', 2).evaluate
+    assert_equal true, Condition.new({ 'a' => 1 }, '==', { 'a' => 1 }).evaluate
+    assert_equal true, Condition.new({ 'a' => 2 }, 'contains', 'a').evaluate
+  end
+
   def test_contains_works_on_arrays
     @context = Liquid::Context.new
     @context['array'] = [1, 2, 3, 4, 5]

test/unit/context_unit_test.rb

@@ -70,10 +70,6 @@ class ContextUnitTest < Minitest::Test
     @context = Liquid::Context.new
   end
 
-  def teardown
-    Spy.teardown
-  end
-
   def test_variables
     @context['string'] = 'string'
     assert_equal 'string', @context['string']
@@ -98,12 +94,12 @@ class ContextUnitTest < Minitest::Test
     assert_equal false, @context['bool']
 
     @context['nil'] = nil
-    assert_equal nil, @context['nil']
-    assert_equal nil, @context['nil']
+    assert_nil @context['nil']
+    assert_nil @context['nil']
   end
 
   def test_variables_not_existing
-    assert_equal nil, @context['does_not_exist']
+    assert_nil @context['does_not_exist']
   end
 
   def test_scoping
@@ -185,7 +181,7 @@ class ContextUnitTest < Minitest::Test
     @context['test'] = 'test'
     assert_equal 'test', @context['test']
     @context.pop
-    assert_equal nil, @context['test']
+    assert_nil @context['test']
   end
 
   def test_hierachical_data
@@ -300,7 +296,7 @@ class ContextUnitTest < Minitest::Test
     @context['hash'] = { 'first' => 'Hello' }
 
     assert_equal 1, @context['array.first']
-    assert_equal nil, @context['array["first"]']
+    assert_nil @context['array["first"]']
     assert_equal 'Hello', @context['hash["first"]']
   end
 
@@ -450,14 +446,10 @@ class ContextUnitTest < Minitest::Test
     assert_equal @context, @context['category'].context
   end
 
-  def test_use_empty_instead_of_any_in_interrupt_handling_to_avoid_lots_of_unnecessary_object_allocations
-    mock_any = Spy.on_instance_method(Array, :any?)
-    mock_empty = Spy.on_instance_method(Array, :empty?)
-
-    @context.interrupt?
-
-    refute mock_any.has_been_called?
-    assert mock_empty.has_been_called?
+  def test_interrupt_avoids_object_allocations
+    assert_no_object_allocations do
+      @context.interrupt?
+    end
   end
 
   def test_context_initialization_with_a_proc_in_environment
@@ -476,8 +468,90 @@ class ContextUnitTest < Minitest::Test
     assert_equal 'hi filtered', context.apply_global_filter('hi')
   end
 
+  def test_static_environments_are_read_with_lower_priority_than_environments
+    context = Context.build(
+      static_environments: { 'shadowed' => 'static', 'unshadowed' => 'static' },
+      environments: { 'shadowed' => 'dynamic' }
+    )
+
+    assert_equal 'dynamic', context['shadowed']
+    assert_equal 'static', context['unshadowed']
+  end
+
   def test_apply_global_filter_when_no_global_filter_exist
     context = Context.new
     assert_equal 'hi', context.apply_global_filter('hi')
   end
+
+  def test_new_isolated_subcontext_does_not_inherit_variables
+    super_context = Context.new
+    super_context['my_variable'] = 'some value'
+    subcontext = super_context.new_isolated_subcontext
+
+    assert_nil subcontext['my_variable']
+  end
+
+  def test_new_isolated_subcontext_inherits_static_environment
+    super_context = Context.build(static_environments: { 'my_environment_value' => 'my value' })
+    subcontext = super_context.new_isolated_subcontext
+
+    assert_equal 'my value', subcontext['my_environment_value']
+  end
+
+  def test_new_isolated_subcontext_inherits_resource_limits
+    resource_limits = ResourceLimits.new({})
+    super_context = Context.new({}, {}, {}, false, resource_limits)
+    subcontext = super_context.new_isolated_subcontext
+    assert_equal resource_limits, subcontext.resource_limits
+  end
+
+  def test_new_isolated_subcontext_inherits_exception_renderer
+    super_context = Context.new
+    super_context.exception_renderer = ->(_e) { 'my exception message' }
+    subcontext = super_context.new_isolated_subcontext
+    assert_equal 'my exception message', subcontext.handle_error(Liquid::Error.new)
+  end
+
+  def test_new_isolated_subcontext_does_not_inherit_non_static_registers
+    registers = {
+      my_register: :my_value
+    }
+    super_context = Context.new({}, {}, registers)
+    subcontext = super_context.new_isolated_subcontext
+    assert_nil subcontext.registers[:my_register]
+  end
+
+  def test_new_isolated_subcontext_inherits_static_registers
+    super_context = Context.build(static_registers: { my_register: :my_value })
+    subcontext = super_context.new_isolated_subcontext
+    assert_equal :my_value, subcontext.static_registers[:my_register]
+  end
+
+  def test_new_isolated_subcontext_inherits_filters
+    my_filter = Module.new do
+      def my_filter(*)
+        'my filter result'
+      end
+    end
+
+    super_context = Context.new
+    super_context.add_filters([my_filter])
+    subcontext = super_context.new_isolated_subcontext
+    template = Template.parse('{{ 123 | my_filter }}')
+    assert_equal 'my filter result', template.render(subcontext)
+  end
+
+  private
+
+  def assert_no_object_allocations
+    unless RUBY_ENGINE == 'ruby'
+      skip "stackprof needed to count object allocations"
+    end
+    require 'stackprof'
+
+    profile = StackProf.run(mode: :object) do
+      yield
+    end
+    assert_equal 0, profile[:samples]
+  end
 end # ContextTest

test/unit/lexer_unit_test.rb

@@ -19,7 +19,7 @@ class LexerUnitTest < Minitest::Test
   end
 
   def test_comparison
-    tokens = Lexer.new('== <> contains').tokenize
+    tokens = Lexer.new('== <> contains ').tokenize
     assert_equal [[:comparison, '=='], [:comparison, '<>'], [:comparison, 'contains'], [:end_of_string]], tokens
   end
 

test/unit/partial_cache_unit_test.rb

@@ -0,0 +1,91 @@
+require 'test_helper'
+
+class PartialCacheUnitTest < Minitest::Test
+  def test_uses_the_file_system_register_if_present
+    context = Liquid::Context.build(
+      registers: {
+        file_system: StubFileSystem.new('my_partial' => 'my partial body')
+      }
+    )
+
+    partial = Liquid::PartialCache.load(
+      'my_partial',
+      context: context,
+      parse_context: Liquid::ParseContext.new
+    )
+
+    assert_equal 'my partial body', partial.render
+  end
+
+  def test_reads_from_the_file_system_only_once_per_file
+    file_system = StubFileSystem.new('my_partial' => 'some partial body')
+    context = Liquid::Context.build(
+      registers: { file_system: file_system }
+    )
+
+    2.times do
+      Liquid::PartialCache.load(
+        'my_partial',
+        context: context,
+        parse_context: Liquid::ParseContext.new
+      )
+    end
+
+    assert_equal 1, file_system.file_read_count
+  end
+
+  def test_cache_state_is_stored_per_context
+    parse_context = Liquid::ParseContext.new
+    shared_file_system = StubFileSystem.new(
+      'my_partial' => 'my shared value'
+    )
+    context_one = Liquid::Context.build(
+      registers: {
+        file_system: shared_file_system
+      }
+    )
+    context_two = Liquid::Context.build(
+      registers: {
+        file_system: shared_file_system
+      }
+    )
+
+    2.times do
+      Liquid::PartialCache.load(
+        'my_partial',
+        context: context_one,
+        parse_context: parse_context
+      )
+    end
+
+    Liquid::PartialCache.load(
+      'my_partial',
+      context: context_two,
+      parse_context: parse_context
+    )
+
+    assert_equal 2, shared_file_system.file_read_count
+  end
+
+  def test_cache_is_not_broken_when_a_different_parse_context_is_used
+    file_system = StubFileSystem.new('my_partial' => 'some partial body')
+    context = Liquid::Context.build(
+      registers: { file_system: file_system }
+    )
+
+    Liquid::PartialCache.load(
+      'my_partial',
+      context: context,
+      parse_context: Liquid::ParseContext.new(my_key: 'value one')
+    )
+    Liquid::PartialCache.load(
+      'my_partial',
+      context: context,
+      parse_context: Liquid::ParseContext.new(my_key: 'value two')
+    )
+
+    # Technically what we care about is that the file was parsed twice,
+    # but measuring file reads is an OK proxy for this.
+    assert_equal 1, file_system.file_read_count
+  end
+end

test/unit/strainer_unit_test.rb

@@ -145,4 +145,20 @@ class StrainerUnitTest < Minitest::Test
     Strainer.global_filter(LateAddedFilter)
     assert_equal 'filtered', Strainer.create(nil).invoke('late_added_filter', 'input')
   end
+
+  def test_add_filter_does_not_include_already_included_module
+    mod = Module.new do
+      class << self
+        attr_accessor :include_count
+        def included(mod)
+          self.include_count += 1
+        end
+      end
+      self.include_count = 0
+    end
+    strainer = Context.new.strainer
+    strainer.class.add_filter(mod)
+    strainer.class.add_filter(mod)
+    assert_equal 1, mod.include_count
+  end
 end # StrainerTest

test/unit/tag_unit_test.rb

@@ -18,4 +18,42 @@ class TagUnitTest < Minitest::Test
     tag = Tag.parse("some_tag", "", Tokenizer.new(""), ParseContext.new)
     assert_equal 'some_tag', tag.tag_name
   end
+
+  def test_custom_tags_have_a_default_render_to_output_buffer_method_for_backwards_compatibility
+    klass1 = Class.new(Tag) do
+      def render(*)
+        'hello'
+      end
+    end
+
+    with_custom_tag('blabla', klass1) do
+      template = Liquid::Template.parse("{% blabla %}")
+
+      assert_equal 'hello', template.render
+
+      buf = ''
+      output = template.render({}, output: buf)
+      assert_equal 'hello', output
+      assert_equal 'hello', buf
+      assert_equal buf.object_id, output.object_id
+    end
+
+    klass2 = Class.new(klass1) do
+      def render(*)
+        'foo' + super + 'bar'
+      end
+    end
+
+    with_custom_tag('blabla', klass2) do
+      template = Liquid::Template.parse("{% blabla %}")
+
+      assert_equal 'foohellobar', template.render
+
+      buf = ''
+      output = template.render({}, output: buf)
+      assert_equal 'foohellobar', output
+      assert_equal 'foohellobar', buf
+      assert_equal buf.object_id, output.object_id
+    end
+  end
 end