Fix leaking error when comparison leads to TypeError

This could be used to preserve the old default of rendering
non-Liquid::Error messages or for providing default behaviour like error
reporting which could be missed if the exception renderer needed to be
specified on each render.

.travis.yml

@@ -1,15 +1,20 @@
 language: ruby
 
 rvm:
-  - 2.0
   - 2.1
   - 2.2
+  - 2.3.3
   - ruby-head
   - jruby-head
 #  - rbx-2
 
 sudo: false
 
+addons:
+  apt:
+    packages:
+    - libgmp3-dev
+
 matrix:
   allow_failures:
     - rvm: jruby-head

CONTRIBUTING.md

@@ -4,23 +4,22 @@
 
 * Bugfixes
 * Performance improvements
-* Features which are likely to be useful to the majority of Liquid users
+* Features that are likely to be useful to the majority of Liquid users
 
 ## Things we won't merge
 
-* Code which introduces considerable performance degrations
-* Code which touches performance critical parts of Liquid and comes without benchmarks
-* Features which are not important for most people (we want to keep the core Liquid code small and tidy)
-* Features which can easily be implemented on top of Liquid (for example as a custom filter or custom filesystem)
-* Code which comes without tests
-* Code which breaks existing tests
+* Code that introduces considerable performance degrations
+* Code that touches performance-critical parts of Liquid and comes without benchmarks
+* Features that are not important for most people (we want to keep the core Liquid code small and tidy)
+* Features that can easily be implemented on top of Liquid (for example as a custom filter or custom filesystem)
+* Code that does not include tests
+* Code that breaks existing tests
 
 ## Workflow
 
 * Fork the Liquid repository
 * Create a new branch in your fork
-* If it makes sense, add tests for your code and run a performance benchmark
-* Make sure all tests pass
+* If it makes sense, add tests for your code and/or run a performance benchmark
+* Make sure all tests pass (`bundle exec rake`)
 * Create a pull request
-* In the description, ping one of [@boourns](https://github.com/boourns), [@fw42](https://github.com/fw42), [@camilo](https://github.com/camilo), [@dylanahsmith](https://github.com/dylanahsmith), or [@arthurnn](https://github.com/arthurnn) and ask for a code review.
 

Gemfile

@@ -9,6 +9,6 @@ group :test do
   gem 'rubocop', '0.34.2'
 
   platform :mri do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: '2570693d8d03faa0df9160ec74348a7149436df3'
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'bd53db95de3d44d631e7c5a267c3d934e66107dd'
   end
 end

History.md

@@ -1,8 +1,14 @@
 # Liquid Change Log
 
-## 4.0.0 / not yet released / branch "master"
+## 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]
+* Ruby 2.0 support dropped (#832) [Dylan Thacker-Smith]
+* Add to_number Drop method to allow custom drops to work with number filters (#731)
+* Add strict_variables and strict_filters options to detect undefined references (#691)
+* Improve loop performance (#681) [Florian Weingarten]
+* Rename Drop method `before_method` to `liquid_method_missing` (#661) [Thierry Joyal]
 * Add url_decode filter to invert url_encode (#645) [Larry Archer]
 * Add global_filter to apply a filter to all output (#610) [Loren Hale]
 * Add compact filter (#600) [Carson Reinke]
@@ -15,9 +21,12 @@
 * 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`
-* Rename Drop method `before_method` as `liquid_method_missing` (#661) [Thierry Joyal]
+* Liquid::Template.register_filter raises when the module overrides registered public methods as private or protected (#705) [Gaurav Chande]
 
 ### Fixed
+* 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]
 * Fix sort filter behaviour with empty array input (#652) [Marcel Cary]
 * Fix test failure under certain timezones (#631) [Dylan Thacker-Smith]
 * Fix bug in uniq filter (#595) [Florian Weingarten]

README.md

@@ -73,3 +73,34 @@ This is useful for doing things like enabling strict mode only in the theme edit
 
 It is recommended that you enable `:strict` or `:warn` mode on new apps to stop invalid templates from being created.
 It is also recommended that you use it in the template editors of existing apps to give editors better error messages.
+
+### Undefined variables and filters
+
+By default, the renderer doesn't raise or in any other way notify you if some variables or filters are missing, i.e. not passed to the `render` method.
+You can improve this situation by passing `strict_variables: true` and/or `strict_filters: true` options to the `render` method.
+When one of these options is set to true, all errors about undefined variables and undefined filters will be stored in `errors` array of a `Liquid::Template` instance.
+Here are some examples:
+
+```ruby
+template = Liquid::Template.parse("{{x}} {{y}} {{z.a}} {{z.b}}")
+template.render({ 'x' => 1, 'z' => { 'a' => 2 } }, { strict_variables: true })
+#=> '1  2 ' # when a variable is undefined, it's rendered as nil
+template.errors
+#=> [#<Liquid::UndefinedVariable: Liquid error: undefined variable y>, #<Liquid::UndefinedVariable: Liquid error: undefined variable b>]
+```
+
+```ruby
+template = Liquid::Template.parse("{{x | filter1 | upcase}}")
+template.render({ 'x' => 'foo' }, { strict_filters: true })
+#=> '' # when at least one filter in the filter chain is undefined, a whole expression is rendered as nil
+template.errors
+#=> [#<Liquid::UndefinedFilter: Liquid error: undefined filter filter1>]
+```
+
+If you want to raise on a first exception instead of pushing all of them in `errors`, you can use `render!` method:
+
+```ruby
+template = Liquid::Template.parse("{{x}} {{y}}")
+template.render!({ 'x' => 1}, { strict_variables: true })
+#=> Liquid::UndefinedVariable: Liquid error: undefined variable y
+```

circle.yml

@@ -1,3 +1,3 @@
 machine:
   ruby:
-    version: ruby-2.0
+    version: ruby-2.1

lib/liquid.rb

@@ -24,6 +24,7 @@ module Liquid
   ArgumentSeparator           = ','.freeze
   FilterArgumentSeparator     = ':'.freeze
   VariableAttributeSeparator  = '.'.freeze
+  WhitespaceControl           = '-'.freeze
   TagStart                    = /\{\%/
   TagEnd                      = /\%\}/
   VariableSignature           = /\(?[\w\-\.\[\]]\)?/
@@ -34,7 +35,7 @@ module Liquid
   QuotedString                = /"[^"]*"|'[^']*'/
   QuotedFragment              = /#{QuotedString}|(?:[^\s,\|'"]|#{QuotedString})+/o
   TagAttributes               = /(\w+)\s*\:\s*(#{QuotedFragment})/o
-  AnyStartingTag              = /\{\{|\{\%/
+  AnyStartingTag              = /#{TagStart}|#{VariableStart}/o
   PartialTemplateParser       = /#{TagStart}.*?#{TagEnd}|#{VariableStart}.*?#{VariableIncompleteEnd}/om
   TemplateParser              = /(#{PartialTemplateParser}|#{AnyStartingTag})/om
   VariableParser              = /\[[^\]]+\]|#{VariableSegment}+\??/o

lib/liquid/block_body.rb

@@ -1,7 +1,7 @@
 module Liquid
   class BlockBody
-    FullToken = /\A#{TagStart}\s*(\w+)\s*(.*)?#{TagEnd}\z/om
-    ContentOfVariable = /\A#{VariableStart}(.*)#{VariableEnd}\z/om
+    FullToken = /\A#{TagStart}#{WhitespaceControl}?\s*(\w+)\s*(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
+    ContentOfVariable = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
     TAGSTART = "{%".freeze
     VARSTART = "{{".freeze
 
@@ -18,6 +18,7 @@ module Liquid
         unless token.empty?
           case
           when token.start_with?(TAGSTART)
+            whitespace_handler(token, parse_context)
             if token =~ FullToken
               tag_name = $1
               markup = $2
@@ -35,9 +36,14 @@ module Liquid
               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/)
           end
@@ -48,6 +54,16 @@ module Liquid
       yield nil, nil
     end
 
+    def whitespace_handler(token, parse_context)
+      if token[2] == WhitespaceControl
+        previous_token = @nodelist.last
+        if previous_token.is_a? String
+          previous_token.rstrip!
+        end
+      end
+      parse_context.trim_whitespace = (token[-3] == WhitespaceControl)
+    end
+
     def blank?
       @blank
     end
@@ -76,8 +92,11 @@ module Liquid
           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)
+          output << context.handle_error(e, token.line_number, token.raw)
         end
       end
 

lib/liquid/condition.rb

@@ -113,7 +113,7 @@ module Liquid
       elsif left.respond_to?(operation) && right.respond_to?(operation)
         begin
           left.send(operation, right)
-        rescue ::ArgumentError => e
+        rescue ::ArgumentError, TypeError => e
           raise Liquid::ArgumentError.new(e.message)
         end
       end

lib/liquid/context.rb

@@ -13,7 +13,7 @@ module Liquid
   #   context['bob']  #=> nil  class Context
   class Context
     attr_reader :scopes, :errors, :registers, :environments, :resource_limits
-    attr_accessor :exception_handler, :template_name, :partial, :global_filter
+    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
@@ -21,13 +21,15 @@ module Liquid
       @registers        = registers
       @errors           = []
       @partial          = false
+      @strict_variables = false
       @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
       squash_instance_assigns_with_environments
 
       @this_stack_used = false
 
+      self.exception_renderer = Template.default_exception_renderer
       if rethrow_errors
-        self.exception_handler = ->(e) { raise }
+        self.exception_renderer = ->(e) { raise }
       end
 
       @interrupts = []
@@ -72,31 +74,12 @@ module Liquid
       @interrupts.pop
     end
 
-    def handle_error(e, line_number = nil)
-      if e.is_a?(Liquid::Error)
-        e.template_name ||= template_name
-        e.line_number ||= line_number
-      end
-
-      output = nil
-
-      if exception_handler
-        result = exception_handler.call(e)
-        case result
-        when Exception
-          e = result
-          if e.is_a?(Liquid::Error)
-            e.template_name ||= template_name
-            e.line_number ||= line_number
-          end
-        when String
-          output = result
-        else
-          raise if result
-        end
-      end
+    def handle_error(e, line_number = nil, raw_token = nil)
+      e = internal_error unless e.is_a?(Liquid::Error)
+      e.template_name ||= template_name
+      e.line_number ||= line_number
       errors.push(e)
-      output || Liquid::Error.render(e)
+      exception_renderer.call(e).to_s
     end
 
     def invoke(method, *args)
@@ -205,7 +188,13 @@ module Liquid
     end
 
     def lookup_and_evaluate(obj, key)
-      if (value = obj[key]).is_a?(Proc) && obj.respond_to?(:[]=)
+      if @strict_variables && obj.respond_to?(:key?) && !obj.key?(key)
+        raise Liquid::UndefinedVariable, "undefined variable #{key}"
+      end
+
+      value = obj[key]
+
+      if value.is_a?(Proc) && obj.respond_to?(:[]=)
         obj[key] = (value.arity == 0) ? value.call : value.call(self)
       else
         value
@@ -214,6 +203,13 @@ module Liquid
 
     private
 
+    def internal_error
+      # raise and catch to set backtrace and cause on exception
+      raise Liquid::InternalError, 'internal'
+    rescue Liquid::InternalError => exc
+      exc
+    end
+
     def squash_instance_assigns_with_environments
       @scopes.last.each_key do |k|
         @environments.each do |env|

lib/liquid/drop.rb

@@ -24,8 +24,9 @@ module Liquid
     attr_writer :context
 
     # Catch all for the method
-    def liquid_method_missing(_method)
-      nil
+    def liquid_method_missing(method)
+      return nil unless @context && @context.strict_variables
+      raise Liquid::UndefinedDropMethod, "undefined method #{method}"
     end
 
     # called by liquid to invoke a drop
@@ -61,16 +62,17 @@ module Liquid
     end
 
     def self.invokable_methods
-      unless @invokable_methods
+      @invokable_methods ||= begin
         blacklist = Liquid::Drop.public_instance_methods + [:each]
+
         if include?(Enumerable)
           blacklist += Enumerable.public_instance_methods
           blacklist -= [:sort, :count, :first, :min, :max, :include?]
         end
+
         whitelist = [:to_liquid] + (public_instance_methods - blacklist)
-        @invokable_methods = Set.new(whitelist.map(&:to_s))
+        Set.new(whitelist.map(&:to_s))
       end
-      @invokable_methods
     end
   end
 end

lib/liquid/errors.rb

@@ -17,14 +17,6 @@ module Liquid
       str
     end
 
-    def self.render(e)
-      if e.is_a?(Liquid::Error)
-        e.to_s
-      else
-        "Liquid error: #{e}"
-      end
-    end
-
     private
 
     def message_prefix
@@ -56,4 +48,9 @@ module Liquid
   MemoryError = Class.new(Error)
   ZeroDivisionError = Class.new(Error)
   FloatDomainError = Class.new(Error)
+  UndefinedVariable = Class.new(Error)
+  UndefinedDropMethod = Class.new(Error)
+  UndefinedFilter = Class.new(Error)
+  MethodOverrideError = Class.new(Error)
+  InternalError = Class.new(Error)
 end

lib/liquid/extensions.rb

@@ -25,6 +25,12 @@ class Numeric # :nodoc:
   end
 end
 
+class Range # :nodoc:
+  def to_liquid
+    self
+  end
+end
+
 class Time # :nodoc:
   def to_liquid
     self

lib/liquid/file_system.rb

@@ -8,8 +8,8 @@ module Liquid
   #
   # Example:
   #
-  # Liquid::Template.file_system = Liquid::LocalFileSystem.new(template_path)
-  # liquid = Liquid::Template.parse(template)
+  #   Liquid::Template.file_system = Liquid::LocalFileSystem.new(template_path)
+  #   liquid = Liquid::Template.parse(template)
   #
   # This will parse the template with a LocalFileSystem implementation rooted at 'template_path'.
   class BlankFileSystem
@@ -26,10 +26,10 @@ module Liquid
   #
   # Example:
   #
-  # file_system = Liquid::LocalFileSystem.new("/some/path")
+  #   file_system = Liquid::LocalFileSystem.new("/some/path")
   #
-  # file_system.full_path("mypartial")       # => "/some/path/_mypartial.liquid"
-  # file_system.full_path("dir/mypartial")   # => "/some/path/dir/_mypartial.liquid"
+  #   file_system.full_path("mypartial")       # => "/some/path/_mypartial.liquid"
+  #   file_system.full_path("dir/mypartial")   # => "/some/path/dir/_mypartial.liquid"
   #
   # Optionally in the second argument you can specify a custom pattern for template filenames.
   # The Kernel::sprintf format specification is used.
@@ -37,9 +37,9 @@ module Liquid
   #
   # Example:
   #
-  # file_system = Liquid::LocalFileSystem.new("/some/path", "%s.html")
+  #   file_system = Liquid::LocalFileSystem.new("/some/path", "%s.html")
   #
-  # file_system.full_path("index") # => "/some/path/index.html"
+  #   file_system.full_path("index") # => "/some/path/index.html"
   #
   class LocalFileSystem
     attr_accessor :root
@@ -65,7 +65,7 @@ module Liquid
         File.join(root, @pattern % template_path)
       end
 
-      raise FileSystemError, "Illegal template path '#{File.expand_path(full_path)}'" unless File.expand_path(full_path) =~ /\A#{File.expand_path(root)}/
+      raise FileSystemError, "Illegal template path '#{File.expand_path(full_path)}'" unless File.expand_path(full_path).start_with?(File.expand_path(root))
 
       full_path
     end

lib/liquid/locales/en.yml

@@ -22,3 +22,5 @@
       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"
+    argument:
+      include: "Argument error in tag 'include' - Illegal template name"

lib/liquid/parse_context.rb

@@ -1,7 +1,7 @@
 module Liquid
   class ParseContext
-    attr_accessor :partial, :locale, :line_number
-    attr_reader :warnings, :error_mode
+    attr_accessor :locale, :line_number, :trim_whitespace
+    attr_reader :partial, :warnings, :error_mode
 
     def initialize(options = {})
       @template_options = options ? options.dup : {}

lib/liquid/standardfilters.rb

@@ -65,9 +65,10 @@ module Liquid
       return if input.nil?
       input_str = input.to_s
       length = Utils.to_integer(length)
-      l = length - truncate_string.length
+      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 : input_str
+      input_str.length > length ? input_str[0...l] + truncate_string_str : input_str
     end
 
     def truncatewords(input, words = 15, truncate_string = "...".freeze)
@@ -76,7 +77,7 @@ 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 : input
+      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string.to_s : input
     end
 
     # Split input string into an array of substrings separated by given pattern.
@@ -85,7 +86,7 @@ module Liquid
     #   <div class="summary">{{ post | split '//' | first }}</div>
     #
     def split(input, pattern)
-      input.to_s.split(pattern)
+      input.to_s.split(pattern.to_s)
     end
 
     def strip(input)
@@ -124,9 +125,15 @@ module Liquid
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
       elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
-        ary.sort { |a, b| a[property] <=> b[property] }
-      elsif ary.first.respond_to?(property)
-        ary.sort { |a, b| a.send(property) <=> b.send(property) }
+        ary.sort do |a, b|
+          a = a[property]
+          b = b[property]
+          if a && b
+            a <=> b
+          else
+            a ? -1 : 1
+          end
+        end
       end
     end
 
@@ -141,8 +148,6 @@ module Liquid
         []
       elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
         ary.sort { |a, b| a[property].casecmp(b[property]) }
-      elsif ary.first.respond_to?(property)
-        ary.sort { |a, b| a.send(property).casecmp(b.send(property)) }
       end
     end
 
@@ -191,8 +196,6 @@ module Liquid
         []
       elsif ary.first.respond_to?(:[])
         ary.reject{ |a| a[property].nil? }
-      elsif ary.first.respond_to?(property)
-        ary.reject { |a| a.send(property).nil? }
       end
     end
 
@@ -222,6 +225,9 @@ module Liquid
     end
 
     def concat(input, array)
+      unless array.respond_to?(:to_ary)
+        raise ArgumentError.new("concat filter requires an array argument")
+      end
       InputIterator.new(input).concat(array)
     end
 
@@ -292,6 +298,12 @@ module Liquid
       array.last if array.respond_to?(:last)
     end
 
+    # absolute value
+    def abs(input)
+      result = Utils.to_number(input).abs
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
     # addition
     def plus(input, operand)
       apply_operation(input, operand, :+)
@@ -341,9 +353,12 @@ module Liquid
       raise Liquid::FloatDomainError, e.message
     end
 
-    def default(input, default_value = "".freeze)
-      is_blank = input.respond_to?(:empty?) ? input.empty? : !input
-      is_blank ? default_value : input
+    def default(input, default_value = ''.freeze)
+      if !input || input.respond_to?(:empty?) && input.empty?
+        default_value
+      else
+        input
+      end
     end
 
     private
@@ -373,7 +388,7 @@ module Liquid
       end
 
       def concat(args)
-        to_a.concat args
+        to_a.concat(args)
       end
 
       def reverse

lib/liquid/strainer.rb

@@ -26,14 +26,20 @@ module Liquid
     end
 
     def self.add_filter(filter)
-      raise ArgumentError, "Expected module but got: #{f.class}" unless filter.is_a?(Module)
+      raise ArgumentError, "Expected module but got: #{filter.class}" unless filter.is_a?(Module)
       unless self.class.include?(filter)
-        send(:include, filter)
-        @filter_methods.merge(filter.public_instance_methods.map(&:to_s))
+        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(', ')}"
+        else
+          send(:include, filter)
+          @filter_methods.merge(filter.public_instance_methods.map(&:to_s))
+        end
       end
     end
 
     def self.global_filter(filter)
+      @@strainer_class_cache.clear
       @@global_strainer.add_filter(filter)
     end
 
@@ -48,6 +54,8 @@ module Liquid
     def invoke(method, *args)
       if self.class.invokable?(method)
         send(method, *args)
+      elsif @context && @context.strict_filters
+        raise Liquid::UndefinedFilter, "undefined filter #{method}"
       else
         args.first
       end

lib/liquid/tags/assign.rb

@@ -23,16 +23,28 @@ module Liquid
     def render(context)
       val = @from.render(context)
       context.scopes.last[@to] = val
-
-      inc = val.instance_of?(String) || val.instance_of?(Array) || val.instance_of?(Hash) ? val.length : 1
-      context.resource_limits.assign_score += inc
-
+      context.resource_limits.assign_score += assign_score_of(val)
       ''.freeze
     end
 
     def blank?
       true
     end
+
+    private
+
+    def assign_score_of(val)
+      if val.instance_of?(String)
+        val.length
+      elsif val.instance_of?(Array) || val.instance_of?(Hash)
+        sum = 1
+        # Uses #each to avoid extra allocations.
+        val.each { |child| sum += assign_score_of(child) }
+        sum
+      else
+        1
+      end
+    end
   end
 
   Template.register_tag('assign'.freeze, Assign)

lib/liquid/tags/for.rb

@@ -48,8 +48,10 @@ module Liquid
 
     def initialize(tag_name, markup, options)
       super
+      @from = @limit = nil
       parse_with_selected_parser(markup)
       @for_block = BlockBody.new
+      @else_block = nil
     end
 
     def parse(tokens)

lib/liquid/tags/include.rb

@@ -42,8 +42,9 @@ module Liquid
 
     def render(context)
       template_name = context.evaluate(@template_name_expr)
-      partial = load_cached_partial(template_name, context)
+      raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
 
+      partial = load_cached_partial(template_name, context)
       context_variable_name = template_name.split('/'.freeze).last
 
       variable = if @variable_name_expr

lib/liquid/tags/raw.rb

@@ -6,9 +6,7 @@ module Liquid
     def initialize(tag_name, markup, parse_context)
       super
 
-      unless markup =~ Syntax
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_unexpected_args".freeze, tag: tag_name))
-      end
+      ensure_valid_markup(tag_name, markup, parse_context)
     end
 
     def parse(tokens)
@@ -35,6 +33,14 @@ module Liquid
     def blank?
       @body.empty?
     end
+
+    protected
+
+    def ensure_valid_markup(tag_name, markup, parse_context)
+      unless markup =~ Syntax
+        raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_unexpected_args".freeze, tag: tag_name))
+      end
+    end
   end
 
   Template.register_tag('raw'.freeze, Raw)

lib/liquid/template.rb

@@ -19,8 +19,10 @@ module Liquid
     @@file_system = BlankFileSystem.new
 
     class TagRegistry
+      include Enumerable
+
       def initialize
-        @tags  = {}
+        @tags = {}
         @cache = {}
       end
 
@@ -41,6 +43,10 @@ module Liquid
         @cache.delete(tag_name)
       end
 
+      def each(&block)
+        @tags.each(&block)
+      end
+
       private
 
       def lookup_class(name)
@@ -63,6 +69,11 @@ module Liquid
       # :error raises an error when tainted output is used
       attr_writer :taint_mode
 
+      attr_accessor :default_exception_renderer
+      Template.default_exception_renderer = lambda do |exception|
+        exception
+      end
+
       def file_system
         @@file_system
       end
@@ -80,11 +91,11 @@ module Liquid
       end
 
       def error_mode
-        @error_mode || :lax
+        @error_mode ||= :lax
       end
 
       def taint_mode
-        @taint_mode || :lax
+        @taint_mode ||= :lax
       end
 
       # Pass a module with filter methods which should be available
@@ -107,6 +118,7 @@ module Liquid
     end
 
     def initialize
+      @rethrow_errors = false
       @resource_limits = ResourceLimits.new(self.class.default_resource_limits)
     end
 
@@ -160,7 +172,7 @@ module Liquid
         c = args.shift
 
         if @rethrow_errors
-          c.exception_handler = ->(e) { raise }
+          c.exception_renderer = ->(e) { raise }
         end
 
         c
@@ -181,12 +193,7 @@ module Liquid
 
         registers.merge!(options[:registers]) if options[:registers].is_a?(Hash)
 
-        context.add_filters(options[:filters]) if options[:filters]
-
-        context.global_filter = options[:global_filter] if options[:global_filter]
-
-        context.exception_handler = options[:exception_handler] if options[:exception_handler]
-
+        apply_options_to_context(context, options)
       when Module, Array
         context.add_filters(args.pop)
       end
@@ -235,5 +242,13 @@ module Liquid
         yield
       end
     end
+
+    def apply_options_to_context(context, options)
+      context.add_filters(options[:filters]) if options[:filters]
+      context.global_filter = options[:global_filter] if options[:global_filter]
+      context.exception_renderer = options[:exception_renderer] if options[:exception_renderer]
+      context.strict_variables = options[:strict_variables] if options[:strict_variables]
+      context.strict_filters = options[:strict_filters] if options[:strict_filters]
+    end
   end
 end

lib/liquid/tokenizer.rb

@@ -4,7 +4,7 @@ module Liquid
 
     def initialize(source, line_numbers = false)
       @source = source
-      @line_number = 1 if line_numbers
+      @line_number = line_numbers ? 1 : nil
       @tokens = tokenize
     end
 

lib/liquid/utils.rb

@@ -50,9 +50,13 @@ module Liquid
       when Numeric
         obj
       when String
-        (obj.strip =~ /\A\d+\.\d+\z/) ? BigDecimal.new(obj) : obj.to_i
+        (obj.strip =~ /\A-?\d+\.\d+\z/) ? BigDecimal.new(obj) : obj.to_i
       else
-        0
+        if obj.respond_to?(:to_number)
+          obj.to_number
+        else
+          0
+        end
       end
     end
 

lib/liquid/variable_lookup.rb

@@ -55,9 +55,11 @@ module Liquid
           object = object.send(key).to_liquid
 
           # No key was present with the desired value and it wasn't one of the directly supported
-          # keywords either. The only thing we got left is to return nil
+          # keywords either. The only thing we got left is to return nil or
+          # raise an exception if `strict_variables` option is set to true
         else
-          return nil
+          return nil unless context.strict_variables
+          raise Liquid::UndefinedVariable, "undefined variable #{key}"
         end
 
         # If we are dealing with a drop here we have to

lib/liquid/version.rb

@@ -1,4 +1,4 @@
 # encoding: utf-8
 module Liquid
-  VERSION = "4.0.0.rc1"
+  VERSION = "4.0.0"
 end

liquid.gemspec

@@ -15,6 +15,7 @@ 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_rubygems_version = ">= 1.3.7"
 
   s.test_files  = Dir.glob("{test}/**/*")
@@ -24,6 +25,6 @@ Gem::Specification.new do |s|
 
   s.require_path = "lib"
 
-  s.add_development_dependency 'rake'
+  s.add_development_dependency 'rake', '~> 11.3'
   s.add_development_dependency 'minitest'
 end

test/integration/error_handling_test.rb

@@ -94,7 +94,23 @@ class ErrorHandlingTest < Minitest::Test
       )
     end
 
-    assert_match /Liquid syntax error \(line 4\)/, err.message
+    assert_match(/Liquid syntax error \(line 4\)/, err.message)
+  end
+
+  def test_with_line_numbers_adds_numbers_to_parser_errors_with_whitespace_trim
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse(%q(
+          foobar
+
+          {%- "cat" | foobar -%}
+
+          bla
+        ),
+        line_numbers: true
+      )
+    end
+
+    assert_match(/Liquid syntax error \(line 4\)/, err.message)
   end
 
   def test_parsing_warn_with_line_numbers_adds_numbers_to_lexer_errors
@@ -186,22 +202,40 @@ class ErrorHandlingTest < Minitest::Test
     end
   end
 
-  def test_exception_handler_with_string_result
-    template = Liquid::Template.parse('This is an argument error: {{ errors.argument_error }}')
-    output = template.render({ 'errors' => ErrorDrop.new }, exception_handler: ->(e) { '' })
-    assert_equal 'This is an argument error: ', output
-    assert_equal [ArgumentError], template.errors.map(&:class)
-  end
-
-  class InternalError < Liquid::Error
-  end
-
-  def test_exception_handler_with_exception_result
+  def test_default_exception_renderer_with_internal_error
     template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
-    handler = ->(e) { e.is_a?(Liquid::Error) ? e : InternalError.new('internal') }
-    output = template.render({ 'errors' => ErrorDrop.new }, exception_handler: handler)
+
+    output = template.render({ 'errors' => ErrorDrop.new })
+
     assert_equal 'This is a runtime error: Liquid error (line 1): internal', output
-    assert_equal [InternalError], template.errors.map(&:class)
+    assert_equal [Liquid::InternalError], template.errors.map(&:class)
+  end
+
+  def test_setting_default_exception_renderer
+    old_exception_renderer = Liquid::Template.default_exception_renderer
+    exceptions = []
+    Liquid::Template.default_exception_renderer = ->(e) { exceptions << e; '' }
+    template = Liquid::Template.parse('This is a runtime error: {{ errors.argument_error }}')
+
+    output = template.render({ 'errors' => ErrorDrop.new })
+
+    assert_equal 'This is a runtime error: ', output
+    assert_equal [Liquid::ArgumentError], template.errors.map(&:class)
+  ensure
+    Liquid::Template.default_exception_renderer = old_exception_renderer if old_exception_renderer
+  end
+
+  def test_exception_renderer_exposing_non_liquid_error
+    template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
+    exceptions = []
+    handler = ->(e) { exceptions << e; e.cause }
+
+    output = template.render({ 'errors' => ErrorDrop.new }, exception_renderer: handler)
+
+    assert_equal 'This is a runtime error: runtime error', output
+    assert_equal [Liquid::InternalError], exceptions.map(&:class)
+    assert_equal exceptions, template.errors
+    assert_equal '#<RuntimeError: runtime error>', exceptions.first.cause.inspect
   end
 
   class TestFileSystem

test/integration/hash_ordering_test.rb

@@ -1,18 +1,18 @@
 require 'test_helper'
 
-module MoneyFilter
-  def money(input)
-    sprintf(' %d$ ', input)
-  end
-end
-
-module CanadianMoneyFilter
-  def money(input)
-    sprintf(' %d$ CAD ', input)
-  end
-end
-
 class HashOrderingTest < Minitest::Test
+  module MoneyFilter
+    def money(input)
+      sprintf(' %d$ ', input)
+    end
+  end
+
+  module CanadianMoneyFilter
+    def money(input)
+      sprintf(' %d$ CAD ', input)
+    end
+  end
+
   include Liquid
 
   def test_global_register_order

test/integration/security_test.rb

@@ -9,6 +9,10 @@ end
 class SecurityTest < Minitest::Test
   include Liquid
 
+  def setup
+    @assigns = {}
+  end
+
   def test_no_instance_eval
     text = %( {{ '1+1' | instance_eval }} )
     expected = %( 1+1 )

test/integration/standard_filter_test.rb

@@ -41,6 +41,16 @@ class TestEnumerable < Liquid::Drop
   end
 end
 
+class NumberLikeThing < Liquid::Drop
+  def initialize(amount)
+    @amount = amount
+  end
+
+  def to_number
+    @amount
+  end
+end
+
 class StandardFiltersTest < Minitest::Test
   include Liquid
 
@@ -105,15 +115,15 @@ class StandardFiltersTest < Minitest::Test
     assert_equal '...', @filters.truncate('1234567890', 0)
     assert_equal '1234567890', @filters.truncate('1234567890')
     assert_equal "测试...", @filters.truncate("测试测试测试测试", 5)
+    assert_equal '12341', @filters.truncate("1234567890", 5, 1)
   end
 
   def test_split
     assert_equal ['12', '34'], @filters.split('12~34', '~')
     assert_equal ['A? ', ' ,Z'], @filters.split('A? ~ ~ ~ ,Z', '~ ~ ~')
     assert_equal ['A?Z'], @filters.split('A?Z', '~')
-    # Regexp works although Liquid does not support.
-    assert_equal ['A', 'Z'], @filters.split('AxZ', /x/)
     assert_equal [], @filters.split(nil, ' ')
+    assert_equal ['A', 'Z'], @filters.split('A1Z', 1)
   end
 
   def test_escape
@@ -144,6 +154,7 @@ class StandardFiltersTest < Minitest::Test
     assert_equal 'one two three', @filters.truncatewords('one two three')
     assert_equal 'Two small (13&#8221; x 5.5&#8221; x 10&#8221; high) baskets fit inside one large basket (13&#8221;...', @filters.truncatewords('Two small (13&#8221; x 5.5&#8221; x 10&#8221; high) baskets fit inside one large basket (13&#8221; x 16&#8221; x 10.5&#8221; high) with cover.', 15)
     assert_equal "测试测试测试测试", @filters.truncatewords('测试测试测试测试', 5)
+    assert_equal 'one two1', @filters.truncatewords("one two three", 2, 1)
   end
 
   def test_strip_html
@@ -166,6 +177,24 @@ 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_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(input, "price")
+  end
+
   def test_sort_empty_array
     assert_equal [], @filters.sort([], "a")
   end
@@ -364,20 +393,38 @@ class StandardFiltersTest < Minitest::Test
   def test_plus
     assert_template_result "2", "{{ 1 | plus:1 }}"
     assert_template_result "2.0", "{{ '1' | plus:'1.0' }}"
+
+    assert_template_result "5", "{{ price | plus:'2' }}", 'price' => NumberLikeThing.new(3)
   end
 
   def test_minus
     assert_template_result "4", "{{ input | minus:operand }}", 'input' => 5, 'operand' => 1
     assert_template_result "2.3", "{{ '4.3' | minus:'2' }}"
+
+    assert_template_result "5", "{{ price | minus:'2' }}", 'price' => NumberLikeThing.new(7)
+  end
+
+  def test_abs
+    assert_template_result "17", "{{ 17 | abs }}"
+    assert_template_result "17", "{{ -17 | abs }}"
+    assert_template_result "17", "{{ '17' | abs }}"
+    assert_template_result "17", "{{ '-17' | abs }}"
+    assert_template_result "0", "{{ 0 | abs }}"
+    assert_template_result "0", "{{ '0' | abs }}"
+    assert_template_result "17.42", "{{ 17.42 | abs }}"
+    assert_template_result "17.42", "{{ -17.42 | abs }}"
+    assert_template_result "17.42", "{{ '17.42' | abs }}"
+    assert_template_result "17.42", "{{ '-17.42' | abs }}"
   end
 
   def test_times
     assert_template_result "12", "{{ 3 | times:4 }}"
     assert_template_result "0", "{{ 'foo' | times:4 }}"
-
     assert_template_result "6", "{{ '2.1' | times:3 | replace: '.','-' | plus:0}}"
-
     assert_template_result "7.25", "{{ 0.0725 | times:100 }}"
+    assert_template_result "-7.25", '{{ "-0.0725" | times:100 }}'
+    assert_template_result "7.25", '{{ "-0.0725" | times: -100 }}'
+    assert_template_result "4", "{{ price | times:2 }}", 'price' => NumberLikeThing.new(2)
   end
 
   def test_divided_by
@@ -391,6 +438,8 @@ class StandardFiltersTest < Minitest::Test
     assert_raises(Liquid::ZeroDivisionError) do
       assert_template_result "4", "{{ 1 | modulo: 0 }}"
     end
+
+    assert_template_result "5", "{{ price | divided_by:2 }}", 'price' => NumberLikeThing.new(10)
   end
 
   def test_modulo
@@ -398,6 +447,8 @@ class StandardFiltersTest < Minitest::Test
     assert_raises(Liquid::ZeroDivisionError) do
       assert_template_result "4", "{{ 1 | modulo: 0 }}"
     end
+
+    assert_template_result "1", "{{ price | modulo:2 }}", 'price' => NumberLikeThing.new(3)
   end
 
   def test_round
@@ -407,6 +458,9 @@ class StandardFiltersTest < Minitest::Test
     assert_raises(Liquid::FloatDomainError) do
       assert_template_result "4", "{{ 1.0 | divided_by: 0.0 | round }}"
     end
+
+    assert_template_result "5", "{{ price | round }}", 'price' => NumberLikeThing.new(4.6)
+    assert_template_result "4", "{{ price | round }}", 'price' => NumberLikeThing.new(4.3)
   end
 
   def test_ceil
@@ -415,6 +469,8 @@ class StandardFiltersTest < Minitest::Test
     assert_raises(Liquid::FloatDomainError) do
       assert_template_result "4", "{{ 1.0 | divided_by: 0.0 | ceil }}"
     end
+
+    assert_template_result "5", "{{ price | ceil }}", 'price' => NumberLikeThing.new(4.6)
   end
 
   def test_floor
@@ -423,6 +479,8 @@ class StandardFiltersTest < Minitest::Test
     assert_raises(Liquid::FloatDomainError) do
       assert_template_result "4", "{{ 1.0 | divided_by: 0.0 | floor }}"
     end
+
+    assert_template_result "5", "{{ price | floor }}", 'price' => NumberLikeThing.new(5.4)
   end
 
   def test_append
@@ -436,8 +494,7 @@ class StandardFiltersTest < Minitest::Test
     assert_equal [1, 2, 'a'],  @filters.concat([1, 2], ['a'])
     assert_equal [1, 2, 10],   @filters.concat([1, 2], [10])
 
-    assert_raises(TypeError) do
-      # no implicit conversion of Fixnum into Array
+    assert_raises(Liquid::ArgumentError, "concat filter requires an array argument") do
       @filters.concat([1, 2], 10)
     end
   end

test/integration/tags/include_tag_test.rb

@@ -217,6 +217,17 @@ class IncludeTagTest < Minitest::Test
     end
   end
 
+  def test_render_raise_argument_error_when_template_is_undefined
+    assert_raises(Liquid::ArgumentError) do
+      template = Liquid::Template.parse('{% include undefined_variable %}')
+      template.render!
+    end
+    assert_raises(Liquid::ArgumentError) do
+      template = Liquid::Template.parse('{% include nil %}')
+      template.render!
+    end
+  end
+
   def test_including_via_variable_value
     assert_template_result "from TestFileSystem", "{% assign page = 'pick_a_source' %}{% include page %}"
 

test/integration/tags/raw_tag_test.rb

@@ -24,8 +24,8 @@ class RawTagTest < Minitest::Test
   end
 
   def test_invalid_raw
-    assert_match_syntax_error /tag was never closed/, '{% raw %} foo'
-    assert_match_syntax_error /Valid syntax/, '{% raw } foo {% endraw %}'
-    assert_match_syntax_error /Valid syntax/, '{% raw } foo %}{% endraw %}'
+    assert_match_syntax_error(/tag was never closed/, '{% raw %} foo')
+    assert_match_syntax_error(/Valid syntax/, '{% raw } foo {% endraw %}')
+    assert_match_syntax_error(/Valid syntax/, '{% raw } foo %}{% endraw %}')
   end
 end

test/integration/template_test.rb

@@ -27,6 +27,12 @@ class ErroneousDrop < Liquid::Drop
   end
 end
 
+class DropWithUndefinedMethod < Liquid::Drop
+  def foo
+    'foo'
+  end
+end
+
 class TemplateTest < Minitest::Test
   include Liquid
 
@@ -133,6 +139,17 @@ class TemplateTest < Minitest::Test
     refute_nil t.resource_limits.assign_score
   end
 
+  def test_resource_limits_assign_score_nested
+    t = Template.parse("{% assign foo = 'aaaa' | reverse %}")
+
+    t.resource_limits.assign_score_limit = 3
+    assert_equal "Liquid error: Memory limits exceeded", t.render
+    assert t.resource_limits.reached?
+
+    t.resource_limits.assign_score_limit = 5
+    assert_equal "", t.render!
+  end
+
   def test_resource_limits_aborts_rendering_after_first_error
     t = Template.parse("{% for a in (1..100) %} foo1 {% endfor %} bar {% for a in (1..100) %} foo2 {% endfor %}")
     t.resource_limits.render_score_limit = 50
@@ -198,16 +215,20 @@ class TemplateTest < Minitest::Test
     assert_equal 'ruby error in drop', e.message
   end
 
-  def test_exception_handler_doesnt_reraise_if_it_returns_false
+  def test_exception_renderer_that_returns_string
     exception = nil
-    Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_handler: ->(e) { exception = e; false })
+    handler = ->(e) { exception = e; '<!-- error -->' }
+
+    output = Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_renderer: handler)
+
     assert exception.is_a?(Liquid::ZeroDivisionError)
+    assert_equal '<!-- error -->', output
   end
 
-  def test_exception_handler_does_reraise_if_it_returns_true
+  def test_exception_renderer_that_raises
     exception = nil
     assert_raises(Liquid::ZeroDivisionError) do
-      Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_handler: ->(e) { exception = e; true })
+      Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_renderer: ->(e) { exception = e; raise })
     end
     assert exception.is_a?(Liquid::ZeroDivisionError)
   end
@@ -225,4 +246,78 @@ class TemplateTest < Minitest::Test
 
     assert_equal 'BOB filtered', rendered_template
   end
+
+  def test_undefined_variables
+    t = Template.parse("{{x}} {{y}} {{z.a}} {{z.b}} {{z.c.d}}")
+    result = t.render({ 'x' => 33, 'z' => { 'a' => 32, 'c' => { 'e' => 31 } } }, { strict_variables: true })
+
+    assert_equal '33  32  ', result
+    assert_equal 3, t.errors.count
+    assert_instance_of Liquid::UndefinedVariable, t.errors[0]
+    assert_equal 'Liquid error: undefined variable y', t.errors[0].message
+    assert_instance_of Liquid::UndefinedVariable, t.errors[1]
+    assert_equal 'Liquid error: undefined variable b', t.errors[1].message
+    assert_instance_of Liquid::UndefinedVariable, t.errors[2]
+    assert_equal 'Liquid error: undefined variable d', t.errors[2].message
+  end
+
+  def test_undefined_variables_raise
+    t = Template.parse("{{x}} {{y}} {{z.a}} {{z.b}} {{z.c.d}}")
+
+    assert_raises UndefinedVariable do
+      t.render!({ 'x' => 33, 'z' => { 'a' => 32, 'c' => { 'e' => 31 } } }, { strict_variables: true })
+    end
+  end
+
+  def test_undefined_drop_methods
+    d = DropWithUndefinedMethod.new
+    t = Template.new.parse('{{ foo }} {{ woot }}')
+    result = t.render(d, { strict_variables: true })
+
+    assert_equal 'foo ', result
+    assert_equal 1, t.errors.count
+    assert_instance_of Liquid::UndefinedDropMethod, t.errors[0]
+  end
+
+  def test_undefined_drop_methods_raise
+    d = DropWithUndefinedMethod.new
+    t = Template.new.parse('{{ foo }} {{ woot }}')
+
+    assert_raises UndefinedDropMethod do
+      t.render!(d, { strict_variables: true })
+    end
+  end
+
+  def test_undefined_filters
+    t = Template.parse("{{a}} {{x | upcase | somefilter1 | somefilter2 | somefilter3}}")
+    filters = Module.new do
+      def somefilter3(v)
+        "-#{v}-"
+      end
+    end
+    result = t.render({ 'a' => 123, 'x' => 'foo' }, { filters: [filters], strict_filters: true })
+
+    assert_equal '123 ', result
+    assert_equal 1, t.errors.count
+    assert_instance_of Liquid::UndefinedFilter, t.errors[0]
+    assert_equal 'Liquid error: undefined filter somefilter1', t.errors[0].message
+  end
+
+  def test_undefined_filters_raise
+    t = Template.parse("{{x | somefilter1 | upcase | somefilter2}}")
+
+    assert_raises UndefinedFilter do
+      t.render!({ 'x' => 'foo' }, { strict_filters: true })
+    end
+  end
+
+  def test_using_range_literal_works_as_expected
+    t = Template.parse("{% assign foo = (x..y) %}{{ foo }}")
+    result = t.render({ 'x' => 1, 'y' => 5 })
+    assert_equal '1..5', result
+
+    t = Template.parse("{% assign nums = (x..y) %}{% for num in nums %}{{ num }}{% endfor %}")
+    result = t.render({ 'x' => 1, 'y' => 5 })
+    assert_equal '12345', result
+  end
 end

test/integration/trim_mode_test.rb

@@ -0,0 +1,525 @@
+require 'test_helper'
+
+class TrimModeTest < Minitest::Test
+  include Liquid
+
+  # Make sure the trim isn't applied to standard output
+  def test_standard_output
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {{ 'John' }}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          John
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_variable_output_with_multiple_blank_lines
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+
+
+          {{- 'John' -}}
+
+
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>John</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_tag_output_with_multiple_blank_lines
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+
+
+          {%- if true -%}
+          yes
+          {%- endif -%}
+
+
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>yes</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  # Make sure the trim isn't applied to standard tags
+  def test_standard_tags
+    whitespace = '          '
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {% if true %}
+          yes
+          {% endif %}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+#{whitespace}
+          yes
+#{whitespace}
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {% if false %}
+          no
+          {% endif %}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+#{whitespace}
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  # Make sure the trim isn't too agressive
+  def test_no_trim_output
+    text = '<p>{{- \'John\' -}}</p>'
+    expected = '<p>John</p>'
+    assert_template_result(expected, text)
+  end
+
+  # Make sure the trim isn't too agressive
+  def test_no_trim_tags
+    text = '<p>{%- if true -%}yes{%- endif -%}</p>'
+    expected = '<p>yes</p>'
+    assert_template_result(expected, text)
+
+    text = '<p>{%- if false -%}no{%- endif -%}</p>'
+    expected = '<p></p>'
+    assert_template_result(expected, text)
+  end
+
+  def test_single_line_outer_tag
+    text = '<p> {%- if true %} yes {% endif -%} </p>'
+    expected = '<p> yes </p>'
+    assert_template_result(expected, text)
+
+    text = '<p> {%- if false %} no {% endif -%} </p>'
+    expected = '<p></p>'
+    assert_template_result(expected, text)
+  end
+
+  def test_single_line_inner_tag
+    text = '<p> {% if true -%} yes {%- endif %} </p>'
+    expected = '<p> yes </p>'
+    assert_template_result(expected, text)
+
+    text = '<p> {% if false -%} no {%- endif %} </p>'
+    expected = '<p>  </p>'
+    assert_template_result(expected, text)
+  end
+
+  def test_single_line_post_tag
+    text = '<p> {% if true -%} yes {% endif -%} </p>'
+    expected = '<p> yes </p>'
+    assert_template_result(expected, text)
+
+    text = '<p> {% if false -%} no {% endif -%} </p>'
+    expected = '<p> </p>'
+    assert_template_result(expected, text)
+  end
+
+  def test_single_line_pre_tag
+    text = '<p> {%- if true %} yes {%- endif %} </p>'
+    expected = '<p> yes </p>'
+    assert_template_result(expected, text)
+
+    text = '<p> {%- if false %} no {%- endif %} </p>'
+    expected = '<p> </p>'
+    assert_template_result(expected, text)
+  end
+
+  def test_pre_trim_output
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {{- 'John' }}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>John
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_pre_trim_tags
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if true %}
+          yes
+          {%- endif %}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          yes
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if false %}
+          no
+          {%- endif %}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_post_trim_output
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {{ 'John' -}}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          John</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_post_trim_tags
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {% if true -%}
+          yes
+          {% endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          yes
+          </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {% if false -%}
+          no
+          {% endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_pre_and_post_trim_tags
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if true %}
+          yes
+          {% endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          yes
+          </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if false %}
+          no
+          {% endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p></p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_post_and_pre_trim_tags
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {% if true -%}
+          yes
+          {%- endif %}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+          yes
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    whitespace = '          '
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {% if false -%}
+          no
+          {%- endif %}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>
+#{whitespace}
+        </p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_trim_output
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {{- 'John' -}}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>John</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_trim_tags
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if true -%}
+          yes
+          {%- endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>yes</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if false -%}
+          no
+          {%- endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p></p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_whitespace_trim_output
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {{- 'John' -}},
+          {{- '30' -}}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>John,30</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_whitespace_trim_tags
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if true -%}
+          yes
+          {%- endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>yes</p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {%- if false -%}
+          no
+          {%- endif -%}
+        </p>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p></p>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_complex_trim_output
+    text = <<-END_TEMPLATE
+      <div>
+        <p>
+          {{- 'John' -}}
+          {{- '30' -}}
+        </p>
+        <b>
+          {{ 'John' -}}
+          {{- '30' }}
+        </b>
+        <i>
+          {{- 'John' }}
+          {{ '30' -}}
+        </i>
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+        <p>John30</p>
+        <b>
+          John30
+        </b>
+        <i>John
+          30</i>
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_complex_trim
+    text = <<-END_TEMPLATE
+      <div>
+        {%- if true -%}
+          {%- if true -%}
+            <p>
+              {{- 'John' -}}
+            </p>
+          {%- endif -%}
+        {%- endif -%}
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div><p>John</p></div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+
+  def test_raw_output
+    whitespace = '        '
+    text = <<-END_TEMPLATE
+      <div>
+        {% raw %}
+          {%- if true -%}
+            <p>
+              {{- 'John' -}}
+            </p>
+          {%- endif -%}
+        {% endraw %}
+      </div>
+    END_TEMPLATE
+    expected = <<-END_EXPECTED
+      <div>
+#{whitespace}
+          {%- if true -%}
+            <p>
+              {{- 'John' -}}
+            </p>
+          {%- endif -%}
+#{whitespace}
+      </div>
+    END_EXPECTED
+    assert_template_result(expected, text)
+  end
+end # TrimModeTest

test/unit/block_unit_test.rb

@@ -46,6 +46,8 @@ class BlockUnitTest < Minitest::Test
   def test_with_custom_tag
     Liquid::Template.register_tag("testtag", Block)
     assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
+  ensure
+    Liquid::Template.tags.delete('testtag')
   end
 
   private

test/unit/condition_unit_test.rb

@@ -3,56 +3,65 @@ require 'test_helper'
 class ConditionUnitTest < Minitest::Test
   include Liquid
 
+  def setup
+    @context = Liquid::Context.new
+  end
+
   def test_basic_condition
     assert_equal false, Condition.new(1, '==', 2).evaluate
     assert_equal true,  Condition.new(1, '==', 1).evaluate
   end
 
   def test_default_operators_evalute_true
-    assert_evalutes_true 1, '==', 1
-    assert_evalutes_true 1, '!=', 2
-    assert_evalutes_true 1, '<>', 2
-    assert_evalutes_true 1, '<', 2
-    assert_evalutes_true 2, '>', 1
-    assert_evalutes_true 1, '>=', 1
-    assert_evalutes_true 2, '>=', 1
-    assert_evalutes_true 1, '<=', 2
-    assert_evalutes_true 1, '<=', 1
+    assert_evaluates_true 1, '==', 1
+    assert_evaluates_true 1, '!=', 2
+    assert_evaluates_true 1, '<>', 2
+    assert_evaluates_true 1, '<', 2
+    assert_evaluates_true 2, '>', 1
+    assert_evaluates_true 1, '>=', 1
+    assert_evaluates_true 2, '>=', 1
+    assert_evaluates_true 1, '<=', 2
+    assert_evaluates_true 1, '<=', 1
     # negative numbers
-    assert_evalutes_true 1, '>', -1
-    assert_evalutes_true -1, '<', 1
-    assert_evalutes_true 1.0, '>', -1.0
-    assert_evalutes_true -1.0, '<', 1.0
+    assert_evaluates_true 1, '>', -1
+    assert_evaluates_true (-1), '<', 1
+    assert_evaluates_true 1.0, '>', -1.0
+    assert_evaluates_true (-1.0), '<', 1.0
   end
 
   def test_default_operators_evalute_false
-    assert_evalutes_false 1, '==', 2
-    assert_evalutes_false 1, '!=', 1
-    assert_evalutes_false 1, '<>', 1
-    assert_evalutes_false 1, '<', 0
-    assert_evalutes_false 2, '>', 4
-    assert_evalutes_false 1, '>=', 3
-    assert_evalutes_false 2, '>=', 4
-    assert_evalutes_false 1, '<=', 0
-    assert_evalutes_false 1, '<=', 0
+    assert_evaluates_false 1, '==', 2
+    assert_evaluates_false 1, '!=', 1
+    assert_evaluates_false 1, '<>', 1
+    assert_evaluates_false 1, '<', 0
+    assert_evaluates_false 2, '>', 4
+    assert_evaluates_false 1, '>=', 3
+    assert_evaluates_false 2, '>=', 4
+    assert_evaluates_false 1, '<=', 0
+    assert_evaluates_false 1, '<=', 0
   end
 
   def test_contains_works_on_strings
-    assert_evalutes_true 'bob', 'contains', 'o'
-    assert_evalutes_true 'bob', 'contains', 'b'
-    assert_evalutes_true 'bob', 'contains', 'bo'
-    assert_evalutes_true 'bob', 'contains', 'ob'
-    assert_evalutes_true 'bob', 'contains', 'bob'
+    assert_evaluates_true 'bob', 'contains', 'o'
+    assert_evaluates_true 'bob', 'contains', 'b'
+    assert_evaluates_true 'bob', 'contains', 'bo'
+    assert_evaluates_true 'bob', 'contains', 'ob'
+    assert_evaluates_true 'bob', 'contains', 'bob'
 
-    assert_evalutes_false 'bob', 'contains', 'bob2'
-    assert_evalutes_false 'bob', 'contains', 'a'
-    assert_evalutes_false 'bob', 'contains', '---'
+    assert_evaluates_false 'bob', 'contains', 'bob2'
+    assert_evaluates_false 'bob', 'contains', 'a'
+    assert_evaluates_false 'bob', 'contains', '---'
   end
 
   def test_invalid_comparation_operator
     assert_evaluates_argument_error 1, '~~', 0
   end
 
+  def test_comparing_hash_and_integer
+    assert_evaluates_argument_error({a: 1}, '>', 1)
+    assert_evaluates_argument_error(1, '>', {a: 1})
+  end
+
   def test_comparation_of_int_and_str
     assert_evaluates_argument_error '1', '>', 0
     assert_evaluates_argument_error '1', '<', 0
@@ -65,29 +74,29 @@ class ConditionUnitTest < Minitest::Test
     @context['array'] = [1, 2, 3, 4, 5]
     array_expr = VariableLookup.new("array")
 
-    assert_evalutes_false array_expr, 'contains', 0
-    assert_evalutes_true array_expr, 'contains', 1
-    assert_evalutes_true array_expr, 'contains', 2
-    assert_evalutes_true array_expr, 'contains', 3
-    assert_evalutes_true array_expr, 'contains', 4
-    assert_evalutes_true array_expr, 'contains', 5
-    assert_evalutes_false array_expr, 'contains', 6
-    assert_evalutes_false array_expr, 'contains', "1"
+    assert_evaluates_false array_expr, 'contains', 0
+    assert_evaluates_true array_expr, 'contains', 1
+    assert_evaluates_true array_expr, 'contains', 2
+    assert_evaluates_true array_expr, 'contains', 3
+    assert_evaluates_true array_expr, 'contains', 4
+    assert_evaluates_true array_expr, 'contains', 5
+    assert_evaluates_false array_expr, 'contains', 6
+    assert_evaluates_false array_expr, 'contains', "1"
   end
 
   def test_contains_returns_false_for_nil_operands
     @context = Liquid::Context.new
-    assert_evalutes_false VariableLookup.new('not_assigned'), 'contains', '0'
-    assert_evalutes_false 0, 'contains', VariableLookup.new('not_assigned')
+    assert_evaluates_false VariableLookup.new('not_assigned'), 'contains', '0'
+    assert_evaluates_false 0, 'contains', VariableLookup.new('not_assigned')
   end
 
   def test_contains_return_false_on_wrong_data_type
-    assert_evalutes_false 1, 'contains', 0
+    assert_evaluates_false 1, 'contains', 0
   end
 
   def test_contains_with_string_left_operand_coerces_right_operand_to_string
-    assert_evalutes_true ' 1 ', 'contains', 1
-    assert_evalutes_false ' 1 ', 'contains', 2
+    assert_evaluates_true ' 1 ', 'contains', 1
+    assert_evaluates_false ' 1 ', 'contains', 2
   end
 
   def test_or_condition
@@ -121,8 +130,8 @@ class ConditionUnitTest < Minitest::Test
   def test_should_allow_custom_proc_operator
     Condition.operators['starts_with'] = proc { |cond, left, right| left =~ %r{^#{right}} }
 
-    assert_evalutes_true 'bob', 'starts_with', 'b'
-    assert_evalutes_false 'bob', 'starts_with', 'o'
+    assert_evaluates_true 'bob', 'starts_with', 'b'
+    assert_evaluates_false 'bob', 'starts_with', 'o'
   ensure
     Condition.operators.delete 'starts_with'
   end
@@ -131,24 +140,24 @@ class ConditionUnitTest < Minitest::Test
     @context = Liquid::Context.new
     @context['one'] = @context['another'] = "gnomeslab-and-or-liquid"
 
-    assert_evalutes_true VariableLookup.new("one"), '==', VariableLookup.new("another")
+    assert_evaluates_true VariableLookup.new("one"), '==', VariableLookup.new("another")
   end
 
   private
 
-  def assert_evalutes_true(left, op, right)
-    assert Condition.new(left, op, right).evaluate(@context || Liquid::Context.new),
+  def assert_evaluates_true(left, op, right)
+    assert Condition.new(left, op, right).evaluate(@context),
       "Evaluated false: #{left} #{op} #{right}"
   end
 
-  def assert_evalutes_false(left, op, right)
-    assert !Condition.new(left, op, right).evaluate(@context || Liquid::Context.new),
+  def assert_evaluates_false(left, op, right)
+    assert !Condition.new(left, op, right).evaluate(@context),
       "Evaluated true: #{left} #{op} #{right}"
   end
 
   def assert_evaluates_argument_error(left, op, right)
     assert_raises(Liquid::ArgumentError) do
-      Condition.new(left, op, right).evaluate(@context || Liquid::Context.new)
+      Condition.new(left, op, right).evaluate(@context)
     end
   end
 end # ConditionTest

test/unit/strainer_unit_test.rb

@@ -77,4 +77,72 @@ class StrainerUnitTest < Minitest::Test
     assert_kind_of b, strainer
     assert_kind_of Liquid::StandardFilters, strainer
   end
+
+  def test_add_filter_when_wrong_filter_class
+    c = Context.new
+    s = c.strainer
+    wrong_filter = ->(v) { v.reverse }
+
+    assert_raises ArgumentError do
+      s.class.add_filter(wrong_filter)
+    end
+  end
+
+  module PrivateMethodOverrideFilter
+    private
+
+    def public_filter
+      "overriden as private"
+    end
+  end
+
+  def test_add_filter_raises_when_module_privately_overrides_registered_public_methods
+    strainer = Context.new.strainer
+
+    error = assert_raises(Liquid::MethodOverrideError) do
+      strainer.class.add_filter(PrivateMethodOverrideFilter)
+    end
+    assert_equal 'Liquid error: Filter overrides registered public methods as non public: public_filter', error.message
+  end
+
+  module ProtectedMethodOverrideFilter
+    protected
+
+    def public_filter
+      "overriden as protected"
+    end
+  end
+
+  def test_add_filter_raises_when_module_overrides_registered_public_method_as_protected
+    strainer = Context.new.strainer
+
+    error = assert_raises(Liquid::MethodOverrideError) do
+      strainer.class.add_filter(ProtectedMethodOverrideFilter)
+    end
+    assert_equal 'Liquid error: Filter overrides registered public methods as non public: public_filter', error.message
+  end
+
+  module PublicMethodOverrideFilter
+    def public_filter
+      "public"
+    end
+  end
+
+  def test_add_filter_does_not_raise_when_module_overrides_previously_registered_method
+    strainer = Context.new.strainer
+    strainer.class.add_filter(PublicMethodOverrideFilter)
+    assert strainer.class.filter_methods.include?('public_filter')
+  end
+
+  module LateAddedFilter
+    def late_added_filter(input)
+      "filtered"
+    end
+  end
+
+  def test_global_filter_clears_cache
+    assert_equal 'input', Strainer.create(nil).invoke('late_added_filter', 'input')
+    Strainer.global_filter(LateAddedFilter)
+    assert_equal 'filtered', Strainer.create(nil).invoke('late_added_filter', 'input')
+  end
 end # StrainerTest

test/unit/template_unit_test.rb

@@ -67,4 +67,12 @@ class TemplateUnitTest < Minitest::Test
     Template.tags.delete('fake')
     assert_nil Template.tags['fake']
   end
+
+  def test_tags_can_be_looped_over
+    Template.register_tag('fake', FakeTag)
+    result = Template.tags.map { |name, klass| [name, klass] }
+    assert result.include?(["fake", "TemplateUnitTest::FakeTag"])
+  ensure
+    Template.tags.delete('fake')
+  end
 end