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Testing Variable Processing and Filter Chain Implementation in Liquid

This test suite validates the Variable class functionality in Liquid, focusing on variable parsing, filter application, and lookup behavior in the template engine. It ensures robust handling of different variable types and filtering operations.

Test Coverage Overview

The test suite provides comprehensive coverage of variable handling in Liquid templating:

Variable creation and parsing validation
Filter chain processing and arguments handling
Support for various data types (strings, integers, floats)
Special character handling and naming conventions
Error mode behavior testing (strict vs lax)

Implementation Analysis

The testing approach uses Minitest framework with systematic verification of the Variable class functionality:

Modular test methods for specific features
Extensive filter chain validation
Edge case handling for different input formats
Variable lookup mechanism testing

Technical Details

Testing infrastructure includes:

Minitest as the testing framework
Custom ParseContext for variable creation
VariableLookup class for nested variable access
Error mode configuration options
Helper methods for variable creation and context management

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases for specific functionality
Comprehensive error handling validation
Clear test method naming conventions
Thorough documentation of expected behavior
Systematic approach to edge case testing

shopify/liquid

test/unit/variable_unit_test.rb

            
# frozen_string_literal: true

require 'test_helper'

class VariableUnitTest < Minitest::Test
  include Liquid

  def test_variable
    var = create_variable('hello')
    assert_equal(VariableLookup.new('hello'), var.name)
  end

  def test_filters
    var = create_variable('hello | textileze')
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['textileze', []]], var.filters)

    var = create_variable('hello | textileze | paragraph')
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['textileze', []], ['paragraph', []]], var.filters)

    var = create_variable(%( hello | strftime: '%Y'))
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['strftime', ['%Y']]], var.filters)

    var = create_variable(%( 'typo' | link_to: 'Typo', true ))
    assert_equal('typo', var.name)
    assert_equal([['link_to', ['Typo', true]]], var.filters)

    var = create_variable(%( 'typo' | link_to: 'Typo', false ))
    assert_equal('typo', var.name)
    assert_equal([['link_to', ['Typo', false]]], var.filters)

    var = create_variable(%( 'foo' | repeat: 3 ))
    assert_equal('foo', var.name)
    assert_equal([['repeat', [3]]], var.filters)

    var = create_variable(%( 'foo' | repeat: 3, 3 ))
    assert_equal('foo', var.name)
    assert_equal([['repeat', [3, 3]]], var.filters)

    var = create_variable(%( 'foo' | repeat: 3, 3, 3 ))
    assert_equal('foo', var.name)
    assert_equal([['repeat', [3, 3, 3]]], var.filters)

    var = create_variable(%( hello | strftime: '%Y, okay?'))
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['strftime', ['%Y, okay?']]], var.filters)

    var = create_variable(%( hello | things: "%Y, okay?", 'the other one'))
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['things', ['%Y, okay?', 'the other one']]], var.filters)
  end

  def test_filter_with_date_parameter
    var = create_variable(%( '2006-06-06' | date: "%m/%d/%Y"))
    assert_equal('2006-06-06', var.name)
    assert_equal([['date', ['%m/%d/%Y']]], var.filters)
  end

  def test_filters_without_whitespace
    var = create_variable('hello | textileze | paragraph')
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['textileze', []], ['paragraph', []]], var.filters)

    var = create_variable('hello|textileze|paragraph')
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['textileze', []], ['paragraph', []]], var.filters)

    var = create_variable("hello|replace:'foo','bar'|textileze")
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['replace', ['foo', 'bar']], ['textileze', []]], var.filters)
  end

  def test_symbol
    var = create_variable("http://disney.com/logo.gif | image: 'med' ", error_mode: :lax)
    assert_equal(VariableLookup.new('http://disney.com/logo.gif'), var.name)
    assert_equal([['image', ['med']]], var.filters)
  end

  def test_string_to_filter
    var = create_variable("'http://disney.com/logo.gif' | image: 'med' ")
    assert_equal('http://disney.com/logo.gif', var.name)
    assert_equal([['image', ['med']]], var.filters)
  end

  def test_string_single_quoted
    var = create_variable(%( "hello" ))
    assert_equal('hello', var.name)
  end

  def test_string_double_quoted
    var = create_variable(%( 'hello' ))
    assert_equal('hello', var.name)
  end

  def test_integer
    var = create_variable(%( 1000 ))
    assert_equal(1000, var.name)
  end

  def test_float
    var = create_variable(%( 1000.01 ))
    assert_equal(1000.01, var.name)
  end

  def test_dashes
    assert_equal(VariableLookup.new('foo-bar'), create_variable('foo-bar').name)
    assert_equal(VariableLookup.new('foo-bar-2'), create_variable('foo-bar-2').name)

    with_error_mode(:strict) do
      assert_raises(Liquid::SyntaxError) { create_variable('foo - bar') }
      assert_raises(Liquid::SyntaxError) { create_variable('-foo') }
      assert_raises(Liquid::SyntaxError) { create_variable('2foo') }
    end
  end

  def test_string_with_special_chars
    var = create_variable(%( 'hello! $!@.;"ddasd" ' ))
    assert_equal('hello! $!@.;"ddasd" ', var.name)
  end

  def test_string_dot
    var = create_variable(%( test.test ))
    assert_equal(VariableLookup.new('test.test'), var.name)
  end

  def test_filter_with_keyword_arguments
    var = create_variable(%( hello | things: greeting: "world", farewell: 'goodbye'))
    assert_equal(VariableLookup.new('hello'), var.name)
    assert_equal([['things', [], { 'greeting' => 'world', 'farewell' => 'goodbye' }]], var.filters)
  end

  def test_lax_filter_argument_parsing
    var = create_variable(%( number_of_comments | pluralize: 'comment': 'comments' ), error_mode: :lax)
    assert_equal(VariableLookup.new('number_of_comments'), var.name)
    assert_equal([['pluralize', ['comment', 'comments']]], var.filters)
  end

  def test_strict_filter_argument_parsing
    with_error_mode(:strict) do
      assert_raises(SyntaxError) do
        create_variable(%( number_of_comments | pluralize: 'comment': 'comments' ))
      end
    end
  end

  def test_output_raw_source_of_variable
    var = create_variable(%( name_of_variable | upcase ))
    assert_equal(" name_of_variable | upcase ", var.raw)
  end

  def test_variable_lookup_interface
    lookup = VariableLookup.new('a.b.c')
    assert_equal('a', lookup.name)
    assert_equal(['b', 'c'], lookup.lookups)
  end

  private

  def create_variable(markup, options = {})
    Variable.new(markup, ParseContext.new(options))
  end
end