Shopify stye guide fixes

* Enabled frozen string literals

* Update rubocop config

* Prefer string interpolation in simple cases

Co-Authored-By: Dylan Thacker-Smith <dylan.smith@shopify.com>

.rubocop_todo.yml

@@ -6,26 +6,6 @@
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 2
-Lint/AmbiguousOperator:
-  Exclude:
-    - 'test/unit/condition_unit_test.rb'
-
-# Offense count: 21
-# Configuration parameters: AllowSafeAssignment.
-Lint/AssignmentInCondition:
-  Exclude:
-    - 'lib/liquid/block_body.rb'
-    - 'lib/liquid/lexer.rb'
-    - 'lib/liquid/standardfilters.rb'
-    - 'lib/liquid/tags/for.rb'
-    - 'lib/liquid/tags/if.rb'
-    - 'lib/liquid/tags/raw.rb'
-    - 'lib/liquid/variable.rb'
-    - 'performance/profile.rb'
-    - 'test/test_helper.rb'
-    - 'test/unit/tokenizer_unit_test.rb'
-
 # Offense count: 2
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
@@ -34,17 +14,6 @@ Lint/InheritException:
   Exclude:
     - 'lib/liquid/interrupts.rb'
 
-# Offense count: 2
-Lint/UselessAssignment:
-  Exclude:
-    - 'performance/shopify/database.rb'
-
-# Offense count: 1
-# Configuration parameters: CheckForMethodsWithNoSideEffects.
-Lint/Void:
-  Exclude:
-    - 'lib/liquid/parse_context.rb'
-
 # Offense count: 98
 # Cop supports --auto-correct.
 # Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
@@ -76,19 +45,4 @@ Style/ClassVars:
   Exclude:
     - 'lib/liquid/condition.rb'
     - 'lib/liquid/strainer.rb'
-    - 'lib/liquid/template.rb'
-
-# Offense count: 1
-# Configuration parameters: AllowCoercion.
-Style/DateTime:
-  Exclude:
-    - 'test/unit/context_unit_test.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'
+    - 'lib/liquid/template.rb'

lib/liquid.rb

@@ -78,6 +78,7 @@ require 'liquid/tokenizer'
 require 'liquid/parse_context'
 require 'liquid/partial_cache'
 require 'liquid/usage'
+require 'liquid/static_registers'
 
 # Load all the tags of the standard library
 #

lib/liquid/block_body.rb

@@ -27,7 +27,7 @@ module Liquid
     end
 
     private def parse_for_liquid_tag(tokenizer, parse_context)
-      while token = tokenizer.shift
+      while (token = tokenizer.shift)
         unless token.empty? || token =~ WhitespaceOrNothing
           unless token =~ LiquidTagToken
             # line isn't empty but didn't match tag syntax, yield and let the
@@ -36,7 +36,7 @@ module Liquid
           end
           tag_name = Regexp.last_match(1)
           markup = Regexp.last_match(2)
-          unless tag = registered_tags[tag_name]
+          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
@@ -52,7 +52,7 @@ module Liquid
     end
 
     private def parse_for_document(tokenizer, parse_context, &block)
-      while token = tokenizer.shift
+      while (token = tokenizer.shift)
         next if token.empty?
         case
         when token.start_with?(TAGSTART)
@@ -74,7 +74,7 @@ module Liquid
             next parse_for_liquid_tag(liquid_tag_tokenizer, parse_context, &block)
           end
 
-          unless tag = registered_tags[tag_name]
+          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
@@ -122,7 +122,7 @@ module Liquid
       context.resource_limits.render_score += @nodelist.length
 
       idx = 0
-      while node = @nodelist[idx]
+      while (node = @nodelist[idx])
         previous_output_size = output.bytesize
 
         case node

lib/liquid/context.rb

@@ -18,18 +18,17 @@ module Liquid
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
     # 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)
+    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {})
+      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments)
     end
 
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_registers = {}, static_environments = {})
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_environments = {})
       @environments = [environments]
       @environments.flatten!
 
       @static_environments = [static_environments].flat_map(&:freeze).freeze
       @scopes              = [(outer_scope || {})]
       @registers           = registers
-      @static_registers    = static_registers.freeze
       @errors              = []
       @partial             = false
       @strict_variables    = false
@@ -137,7 +136,7 @@ module Liquid
       Context.build(
         resource_limits: resource_limits,
         static_environments: static_environments,
-        static_registers: static_registers
+        registers: StaticRegisters.new(registers)
       ).tap do |subcontext|
         subcontext.base_scope_depth = base_scope_depth + 1
         subcontext.exception_renderer = exception_renderer

lib/liquid/drop.rb

@@ -69,7 +69,7 @@ module Liquid
 
         if include?(Enumerable)
           blacklist += Enumerable.public_instance_methods
-          blacklist -= [:sort, :count, :first, :min, :max, :include?]
+          blacklist -= [:sort, :count, :first, :min, :max]
         end
 
         whitelist = [:to_liquid] + (public_instance_methods - blacklist)

lib/liquid/lexer.rb

@@ -33,15 +33,21 @@ module Liquid
       until @ss.eos?
         @ss.skip(WHITESPACE_OR_NOTHING)
         break if @ss.eos?
-        tok = if t = @ss.scan(COMPARISON_OPERATOR) then [:comparison, t]
-        elsif t = @ss.scan(SINGLE_STRING_LITERAL) then [:string, t]
-        elsif t = @ss.scan(DOUBLE_STRING_LITERAL) then [:string, t]
-        elsif t = @ss.scan(NUMBER_LITERAL) then [:number, t]
-        elsif t = @ss.scan(IDENTIFIER) then [:id, t]
-        elsif t = @ss.scan(DOTDOT) then [:dotdot, t]
+        tok = if (t = @ss.scan(COMPARISON_OPERATOR))
+          [:comparison, t]
+        elsif (t = @ss.scan(SINGLE_STRING_LITERAL))
+          [:string, t]
+        elsif (t = @ss.scan(DOUBLE_STRING_LITERAL))
+          [:string, t]
+        elsif (t = @ss.scan(NUMBER_LITERAL))
+          [:number, t]
+        elsif (t = @ss.scan(IDENTIFIER))
+          [:id, t]
+        elsif (t = @ss.scan(DOTDOT))
+          [:dotdot, t]
         else
           c = @ss.getch
-          if s = SPECIALS[c]
+          if (s = SPECIALS[c])
             [s, c]
           else
             raise SyntaxError, "Unexpected character #{c}"

lib/liquid/parse_context.rb

@@ -21,7 +21,6 @@ module Liquid
       @partial = value
       @options = value ? partial_options : @template_options
       @error_mode = @options[:error_mode] || Template.error_mode
-      value
     end
 
     def partial_options

lib/liquid/standardfilters.rb

@@ -327,7 +327,7 @@ module Liquid
     def date(input, format)
       return input if format.to_s.empty?
 
-      return input unless date = Utils.to_date(input)
+      return input unless (date = Utils.to_date(input))
 
       date.strftime(format.to_s)
     end

lib/liquid/static_registers.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Liquid
+  class StaticRegisters
+    attr_reader :static_registers, :registers
+
+    def initialize(registers = {})
+      @static_registers = registers.is_a?(StaticRegisters) ? registers.static_registers : registers.freeze
+      @registers = {}
+    end
+
+    def []=(key, value)
+      @registers[key] = value
+    end
+
+    def [](key)
+      if @registers.key?(key)
+        @registers[key]
+      else
+        @static_registers[key]
+      end
+    end
+
+    def delete(key)
+      @registers.delete(key)
+    end
+
+    def fetch(key, default = nil)
+      key?(key) ? self[key] : default
+    end
+
+    def key?(key)
+      @registers.key?(key) || @static_registers.key?(key)
+    end
+  end
+end

lib/liquid/tags/for.rb

@@ -111,7 +111,7 @@ module Liquid
       @reversed = p.id?('reversed')
 
       while p.look(:id) && p.look(:colon, 1)
-        unless attribute = p.id?('limit') || p.id?('offset')
+        unless (attribute = p.id?('limit') || p.id?('offset'))
           raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_attribute")
         end
         p.consume

lib/liquid/tags/if.rb

@@ -94,7 +94,7 @@ module Liquid
     def parse_binary_comparisons(p)
       condition = parse_comparison(p)
       first_condition = condition
-      while op = (p.id?('and') || p.id?('or'))
+      while (op = (p.id?('and') || p.id?('or')))
         child_condition = parse_comparison(p)
         condition.send(op, child_condition)
         condition = child_condition
@@ -104,7 +104,7 @@ module Liquid
 
     def parse_comparison(p)
       a = Expression.parse(p.expression)
-      if op = p.consume?(:comparison)
+      if (op = p.consume?(:comparison))
         b = Expression.parse(p.expression)
         Condition.new(a, op, b)
       else

lib/liquid/tags/raw.rb

@@ -13,7 +13,7 @@ module Liquid
 
     def parse(tokens)
       @body = +''
-      while token = tokens.shift
+      while (token = tokens.shift)
         if token =~ FullTokenPossiblyInvalid
           @body << Regexp.last_match(1) if Regexp.last_match(1) != ""
           return if block_delimiter == Regexp.last_match(2)

lib/liquid/variable.rb

@@ -110,7 +110,7 @@ module Liquid
       filter_args = []
       keyword_args = nil
       unparsed_args.each do |a|
-        if matches = a.match(JustTagAttributes)
+        if (matches = a.match(JustTagAttributes))
           keyword_args ||= {}
           keyword_args[matches[1]] = Expression.parse(matches[2])
         else

performance/profile.rb

@@ -15,7 +15,7 @@ profiler.run
     end
   end
 
-  if profile_type == :cpu && graph_filename = ENV['GRAPH_FILENAME']
+  if profile_type == :cpu && (graph_filename = ENV['GRAPH_FILENAME'])
     File.open(graph_filename, 'w') do |f|
       StackProf::Report.new(results).print_graphviz(nil, f)
     end

performance/shopify/database.rb

@@ -32,8 +32,8 @@ module Database
       db['article']    = db['blog']['articles'].first
 
       db['cart']       = {
-        'total_price' => db['line_items'].values.inject(0) { |sum, item| sum += item['line_price'] * item['quantity'] },
-        'item_count' => db['line_items'].values.inject(0) { |sum, item| sum += item['quantity'] },
+        'total_price' => db['line_items'].values.inject(0) { |sum, item| sum + item['line_price'] * item['quantity'] },
+        'item_count' => db['line_items'].values.inject(0) { |sum, item| sum + item['quantity'] },
         'items' => db['line_items'].values,
       }
 

test/integration/drop_test.rb

@@ -272,4 +272,11 @@ class DropsTest < Minitest::Test
     assert_equal 'ProductDrop', Liquid::Template.parse("{{ product }}").render!('product' => ProductDrop.new)
     assert_equal 'EnumerableDrop', Liquid::Template.parse('{{ collection }}').render!('collection' => EnumerableDrop.new)
   end
+
+  def test_invokable_methods
+    assert_equal %w(to_liquid catchall user_input context texts).to_set, ProductDrop.invokable_methods
+    assert_equal %w(to_liquid scopes_as_array loop_pos scopes).to_set, ContextDrop.invokable_methods
+    assert_equal %w(to_liquid size max min first count).to_set, EnumerableDrop.invokable_methods
+    assert_equal %w(to_liquid max min sort count first).to_set, RealEnumerableDrop.invokable_methods
+  end
 end # DropsTest

test/integration/error_handling_test.rb

@@ -211,7 +211,10 @@ class ErrorHandlingTest < Minitest::Test
   def test_setting_default_exception_renderer
     old_exception_renderer = Liquid::Template.default_exception_renderer
     exceptions = []
-    Liquid::Template.default_exception_renderer = ->(e) { exceptions << e; '' }
+    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)
@@ -225,7 +228,10 @@ class ErrorHandlingTest < Minitest::Test
   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 }
+    handler = ->(e) {
+      exceptions << e
+      e.cause
+    }
 
     output = template.render({ 'errors' => ErrorDrop.new }, exception_renderer: handler)
 

test/integration/template_test.rb

@@ -81,7 +81,10 @@ class TemplateTest < Minitest::Test
 
   def test_lambda_is_called_once_from_persistent_assigns_over_multiple_parses_and_renders
     t = Template.new
-    t.assigns['number'] = -> { @global ||= 0; @global += 1 }
+    t.assigns['number'] = -> {
+      @global ||= 0
+      @global += 1
+    }
     assert_equal '1', t.parse("{{number}}").render!
     assert_equal '1', t.parse("{{number}}").render!
     assert_equal '1', t.render!
@@ -90,7 +93,10 @@ class TemplateTest < Minitest::Test
 
   def test_lambda_is_called_once_from_custom_assigns_over_multiple_parses_and_renders
     t = Template.new
-    assigns = { 'number' => -> { @global ||= 0; @global += 1 } }
+    assigns = { 'number' => -> {
+                              @global ||= 0
+                              @global += 1
+                            } }
     assert_equal '1', t.parse("{{number}}").render!(assigns)
     assert_equal '1', t.parse("{{number}}").render!(assigns)
     assert_equal '1', t.render!(assigns)
@@ -237,7 +243,10 @@ class TemplateTest < Minitest::Test
 
   def test_exception_renderer_that_returns_string
     exception = nil
-    handler = ->(e) { exception = e; '<!-- error -->' }
+    handler = ->(e) {
+      exception = e
+      '<!-- error -->'
+    }
 
     output = Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_renderer: handler)
 
@@ -248,7 +257,10 @@ class TemplateTest < Minitest::Test
   def test_exception_renderer_that_raises
     exception = nil
     assert_raises(Liquid::ZeroDivisionError) do
-      Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_renderer: ->(e) { exception = e; raise })
+      Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_renderer: ->(e) {
+                                                                                 exception = e
+                                                                                 raise
+                                                                               })
     end
     assert exception.is_a?(Liquid::ZeroDivisionError)
   end

test/test_helper.rb

@@ -9,7 +9,7 @@ require 'liquid.rb'
 require 'liquid/profiler'
 
 mode = :strict
-if env_mode = ENV['LIQUID_PARSER_MODE']
+if (env_mode = ENV['LIQUID_PARSER_MODE'])
   puts "-- #{env_mode.upcase} ERROR MODE"
   mode = env_mode.to_sym
 end

test/unit/condition_unit_test.rb

@@ -26,9 +26,9 @@ 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

test/unit/context_unit_test.rb

@@ -85,7 +85,7 @@ class ContextUnitTest < Minitest::Test
     @context['date'] = Date.today
     assert_equal Date.today, @context['date']
 
-    now = DateTime.now
+    now = Time.now
     @context['datetime'] = now
     assert_equal now, @context['datetime']
 
@@ -405,7 +405,11 @@ class ContextUnitTest < Minitest::Test
   end
 
   def test_lambda_is_called_once
-    @context['callcount'] = proc { @global ||= 0; @global += 1; @global.to_s }
+    @context['callcount'] = proc {
+      @global ||= 0
+      @global += 1
+      @global.to_s
+    }
 
     assert_equal '1', @context['callcount']
     assert_equal '1', @context['callcount']
@@ -415,7 +419,11 @@ class ContextUnitTest < Minitest::Test
   end
 
   def test_nested_lambda_is_called_once
-    @context['callcount'] = { "lambda" => proc { @global ||= 0; @global += 1; @global.to_s } }
+    @context['callcount'] = { "lambda" => proc {
+                                            @global ||= 0
+                                            @global += 1
+                                            @global.to_s
+                                          } }
 
     assert_equal '1', @context['callcount.lambda']
     assert_equal '1', @context['callcount.lambda']
@@ -425,7 +433,11 @@ class ContextUnitTest < Minitest::Test
   end
 
   def test_lambda_in_array_is_called_once
-    @context['callcount'] = [1, 2, proc { @global ||= 0; @global += 1; @global.to_s }, 4, 5]
+    @context['callcount'] = [1, 2, proc {
+                                     @global ||= 0
+                                     @global += 1
+                                     @global.to_s
+                                   }, 4, 5]
 
     assert_equal '1', @context['callcount[2]']
     assert_equal '1', @context['callcount[2]']
@@ -518,15 +530,23 @@ class ContextUnitTest < Minitest::Test
     registers = {
       my_register: :my_value,
     }
-    super_context = Context.new({}, {}, registers)
+    super_context = Context.new({}, {}, StaticRegisters.new(registers))
+    super_context.registers[:my_register] = :my_alt_value
     subcontext = super_context.new_isolated_subcontext
-    assert_nil subcontext.registers[:my_register]
+    assert_equal :my_value, subcontext.registers[:my_register]
   end
 
   def test_new_isolated_subcontext_inherits_static_registers
-    super_context = Context.build(static_registers: { my_register: :my_value })
+    super_context = Context.build(registers: { my_register: :my_value })
     subcontext = super_context.new_isolated_subcontext
-    assert_equal :my_value, subcontext.static_registers[:my_register]
+    assert_equal :my_value, subcontext.registers[:my_register]
+  end
+
+  def test_new_isolated_subcontext_registers_do_not_pollute_context
+    super_context = Context.build(registers: { my_register: :my_value })
+    subcontext = super_context.new_isolated_subcontext
+    subcontext.registers[:my_register] = :my_alt_value
+    assert_equal :my_value, super_context.registers[:my_register]
   end
 
   def test_new_isolated_subcontext_inherits_filters

test/unit/static_registers_unit_test.rb

@@ -0,0 +1,211 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class StaticRegistersUnitTest < Minitest::Test
+  include Liquid
+
+  def set
+    static_register = StaticRegisters.new
+    static_register[nil] = true
+    static_register[1] = :one
+    static_register[:one] = "one"
+    static_register["two"] = "three"
+    static_register["two"] = 3
+    static_register[false] = nil
+
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.registers)
+
+    static_register
+  end
+
+  def test_get
+    static_register = set
+
+    assert_equal true, static_register[nil]
+    assert_equal :one, static_register[1]
+    assert_equal "one", static_register[:one]
+    assert_equal 3, static_register["two"]
+    assert_nil static_register[false]
+    assert_nil static_register["unknown"]
+  end
+
+  def test_delete
+    static_register = set
+
+    assert_equal true, static_register.delete(nil)
+    assert_equal :one, static_register.delete(1)
+    assert_equal "one", static_register.delete(:one)
+    assert_equal 3, static_register.delete("two")
+    assert_nil static_register.delete(false)
+    assert_nil static_register.delete("unknown")
+
+    assert_equal({}, static_register.registers)
+  end
+
+  def test_fetch
+    static_register = set
+
+    assert_equal true, static_register.fetch(nil)
+    assert_equal :one, static_register.fetch(1)
+    assert_equal "one", static_register.fetch(:one)
+    assert_equal 3, static_register.fetch("two")
+    assert_nil static_register.fetch(false)
+    assert_nil static_register.fetch("unknown")
+  end
+
+  def test_fetch_default
+    static_register = StaticRegisters.new
+
+    assert_equal true, static_register.fetch(nil, true)
+    assert_equal :one, static_register.fetch(1, :one)
+    assert_equal "one", static_register.fetch(:one, "one")
+    assert_equal 3, static_register.fetch("two", 3)
+    assert_nil static_register.fetch(false, nil)
+  end
+
+  def test_key
+    static_register = set
+
+    assert_equal true, static_register.key?(nil)
+    assert_equal true, static_register.key?(1)
+    assert_equal true, static_register.key?(:one)
+    assert_equal true, static_register.key?("two")
+    assert_equal true, static_register.key?(false)
+    assert_equal false, static_register.key?("unknown")
+    assert_equal false, static_register.key?(true)
+  end
+
+  def set_with_static
+    static_register = StaticRegisters.new(nil => true, 1 => :one, :one => "one", "two" => 3, false => nil)
+    static_register[nil] = false
+    static_register["two"] = 4
+    static_register[true] = "foo"
+
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+    assert_equal({ nil => false, "two" => 4, true => "foo" }, static_register.registers)
+
+    static_register
+  end
+
+  def test_get_with_static
+    static_register = set_with_static
+
+    assert_equal false, static_register[nil]
+    assert_equal :one, static_register[1]
+    assert_equal "one", static_register[:one]
+    assert_equal 4, static_register["two"]
+    assert_equal "foo", static_register[true]
+    assert_nil static_register[false]
+  end
+
+  def test_delete_with_static
+    static_register = set_with_static
+
+    assert_equal false, static_register.delete(nil)
+    assert_equal 4, static_register.delete("two")
+    assert_equal "foo", static_register.delete(true)
+    assert_nil static_register.delete("unknown")
+    assert_nil static_register.delete(:one)
+
+    assert_equal({}, static_register.registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+  end
+
+  def test_fetch_with_static
+    static_register = set_with_static
+
+    assert_equal false, static_register.fetch(nil)
+    assert_equal :one, static_register.fetch(1)
+    assert_equal "one", static_register.fetch(:one)
+    assert_equal 4, static_register.fetch("two")
+    assert_equal "foo", static_register.fetch(true)
+    assert_nil static_register.fetch(false)
+  end
+
+  def test_key_with_static
+    static_register = set_with_static
+
+    assert_equal true, static_register.key?(nil)
+    assert_equal true, static_register.key?(1)
+    assert_equal true, static_register.key?(:one)
+    assert_equal true, static_register.key?("two")
+    assert_equal true, static_register.key?(false)
+    assert_equal false, static_register.key?("unknown")
+    assert_equal true, static_register.key?(true)
+  end
+
+  def test_static_register_frozen
+    static_register = set_with_static
+
+    static = static_register.static_registers
+
+    assert_raises(RuntimeError) do
+      static["two"] = "foo"
+    end
+
+    assert_raises(RuntimeError) do
+      static["unknown"] = "foo"
+    end
+
+    assert_raises(RuntimeError) do
+      static.delete("two")
+    end
+  end
+
+  def test_new_static_retains_static
+    static_register = StaticRegisters.new(nil => true, 1 => :one, :one => "one", "two" => 3, false => nil)
+    static_register["one"] = 1
+    static_register["two"] = 2
+    static_register["three"] = 3
+
+    new_register = StaticRegisters.new(static_register)
+    assert_equal({}, new_register.registers)
+
+    new_register["one"] = 4
+    new_register["two"] = 5
+    new_register["three"] = 6
+
+    newest_register = StaticRegisters.new(new_register)
+    assert_equal({}, newest_register.registers)
+
+    newest_register["one"] = 7
+    newest_register["two"] = 8
+    newest_register["three"] = 9
+
+    assert_equal({ "one" => 1, "two" => 2, "three" => 3 }, static_register.registers)
+    assert_equal({ "one" => 4, "two" => 5, "three" => 6 }, new_register.registers)
+    assert_equal({ "one" => 7, "two" => 8, "three" => 9 }, newest_register.registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, new_register.static_registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, newest_register.static_registers)
+  end
+
+  def test_multiple_instances_are_unique
+    static_register = StaticRegisters.new(nil => true, 1 => :one, :one => "one", "two" => 3, false => nil)
+    static_register["one"] = 1
+    static_register["two"] = 2
+    static_register["three"] = 3
+
+    new_register = StaticRegisters.new(foo: :bar)
+    assert_equal({}, new_register.registers)
+
+    new_register["one"] = 4
+    new_register["two"] = 5
+    new_register["three"] = 6
+
+    newest_register = StaticRegisters.new(bar: :foo)
+    assert_equal({}, newest_register.registers)
+
+    newest_register["one"] = 7
+    newest_register["two"] = 8
+    newest_register["three"] = 9
+
+    assert_equal({ "one" => 1, "two" => 2, "three" => 3 }, static_register.registers)
+    assert_equal({ "one" => 4, "two" => 5, "three" => 6 }, new_register.registers)
+    assert_equal({ "one" => 7, "two" => 8, "three" => 9 }, newest_register.registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+    assert_equal({ foo: :bar }, new_register.static_registers)
+    assert_equal({ bar: :foo }, newest_register.static_registers)
+  end
+end

test/unit/tokenizer_unit_test.rb

@@ -35,7 +35,7 @@ class TokenizerTest < Minitest::Test
   def tokenize(source)
     tokenizer = Liquid::Tokenizer.new(source)
     tokens = []
-    while t = tokenizer.shift
+    while (t = tokenizer.shift)
       tokens << t
     end
     tokens