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Testing Element Selector Matching Functionality in Capybara

This test suite validates Capybara’s element selector matching functionality, focusing on the #match_selector? and #not_matches_selector? methods. It ensures reliable DOM element selection and verification across different selector types including CSS and XPath.

Test Coverage Overview

The test suite provides comprehensive coverage of element selector matching functionality in Capybara.

Key areas tested include:

Positive and negative selector matching
CSS and XPath selector support
Text content filtering
Custom filter blocks
Default selector behavior
Sibling element selection

Implementation Analysis

The testing approach uses RSpec’s expectation syntax to verify selector matching behavior. Tests are structured around two main specs (#match_selector? and #not_matches_selector?) with various matcher combinations and scenarios. The implementation leverages Capybara’s DSL for element finding and matching verification.

Technical patterns include:

Before hooks for test setup
Let blocks for shared elements
Context blocks for grouped scenarios
Custom filter block testing

Technical Details

Testing tools and configuration:

RSpec as the testing framework
Capybara::SpecHelper for test setup
XPath and CSS selector support
Custom matcher methods (matches_css?, matches_xpath?)
Session-based testing environment
HTML fixture loading (/with_html and /form paths)

Best Practices Demonstrated

The test suite exemplifies several testing best practices in Ruby and Capybara testing.

Notable practices include:

Isolated test cases with clear assertions
Comprehensive edge case coverage
DRY test setup using shared contexts
Clear test descriptions
Consistent assertion patterns
Multiple selector type validation

teamcapybara/capybara

lib/capybara/spec/session/element/matches_selector_spec.rb

            
# frozen_string_literal: true

Capybara::SpecHelper.spec '#match_selector?' do
  let(:element) { @session.find(:xpath, '//span', text: '42') }

  before do
    @session.visit('/with_html')
  end

  it 'should be true if the element matches the given selector' do
    expect(element).to match_selector(:xpath, '//span')
    expect(element).to match_selector(:css, 'span.number')
    expect(element.matches_selector?(:css, 'span.number')).to be true
  end

  it 'should be false if the element does not match the given selector' do
    expect(element).not_to match_selector(:xpath, '//div')
    expect(element).not_to match_selector(:css, 'span.not_a_number')
    expect(element.matches_selector?(:css, 'span.not_a_number')).to be false
  end

  it 'should use default selector' do
    Capybara.default_selector = :css
    expect(element).not_to match_selector('span.not_a_number')
    expect(element).to match_selector('span.number')
  end

  it 'should work with elements located via a sibling selector' do
    sibling = element.sibling(:css, 'span', text: 'Other span')
    expect(sibling).to match_selector(:xpath, '//span')
    expect(sibling).to match_selector(:css, 'span')
  end

  it 'should work with the html element' do
    html = @session.find('/html')
    expect(html).to match_selector(:css, 'html')
  end

  context 'with text' do
    it 'should discard all matches where the given string is not contained' do
      expect(element).to match_selector('//span', text: '42')
      expect(element).not_to match_selector('//span', text: 'Doesnotexist')
    end
  end

  it 'should have css sugar' do
    expect(element.matches_css?('span.number')).to be true
    expect(element.matches_css?('span.not_a_number')).to be false
    expect(element.matches_css?('span.number', text: '42')).to be true
    expect(element.matches_css?('span.number', text: 'Nope')).to be false
  end

  it 'should have xpath sugar' do
    expect(element.matches_xpath?('//span')).to be true
    expect(element.matches_xpath?('//div')).to be false
    expect(element.matches_xpath?('//span', text: '42')).to be true
    expect(element.matches_xpath?('//span', text: 'Nope')).to be false
  end

  it 'should accept selector filters' do
    @session.visit('/form')
    cbox = @session.find(:css, '#form_pets_dog')
    expect(cbox.matches_selector?(:checkbox, id: 'form_pets_dog', option: 'dog', name: 'form[pets][]', checked: true)).to be true
  end

  it 'should accept a custom filter block' do
    @session.visit('/form')
    cbox = @session.find(:css, '#form_pets_dog')
    expect(cbox).to match_selector(:checkbox) { |node| node[:id] == 'form_pets_dog' }
    expect(cbox).not_to match_selector(:checkbox) { |node| node[:id] != 'form_pets_dog' }
    expect(cbox.matches_selector?(:checkbox) { |node| node[:id] == 'form_pets_dog' }).to be true
    expect(cbox.matches_selector?(:checkbox) { |node| node[:id] != 'form_pets_dog' }).to be false
  end
end

Capybara::SpecHelper.spec '#not_matches_selector?' do
  let(:element) { @session.find(:css, 'span', text: 42) }
  before do
    @session.visit('/with_html')
  end

  it 'should be false if the given selector matches the element' do
    expect(element).not_to not_match_selector(:xpath, '//span')
    expect(element).not_to not_match_selector(:css, 'span.number')
    expect(element.not_matches_selector?(:css, 'span.number')).to be false
  end

  it 'should be true if the given selector does not match the element' do
    expect(element).to not_match_selector(:xpath, '//abbr')
    expect(element).to not_match_selector(:css, 'p a#doesnotexist')
    expect(element.not_matches_selector?(:css, 'p a#doesnotexist')).to be true
  end

  it 'should use default selector' do
    Capybara.default_selector = :css
    expect(element).to not_match_selector('p a#doesnotexist')
    expect(element).not_to not_match_selector('span.number')
  end

  context 'with text' do
    it 'should discard all matches where the given string is contained' do
      expect(element).not_to not_match_selector(:css, 'span.number', text: '42')
      expect(element).to not_match_selector(:css, 'span.number', text: 'Doesnotexist')
    end
  end

  it 'should have CSS sugar' do
    expect(element.not_matches_css?('span.number')).to be false
    expect(element.not_matches_css?('p a#doesnotexist')).to be true
    expect(element.not_matches_css?('span.number', text: '42')).to be false
    expect(element.not_matches_css?('span.number', text: 'Doesnotexist')).to be true
  end

  it 'should have xpath sugar' do
    expect(element.not_matches_xpath?('//span')).to be false
    expect(element.not_matches_xpath?('//div')).to be true
    expect(element.not_matches_xpath?('//span', text: '42')).to be false
    expect(element.not_matches_xpath?('//span', text: 'Doesnotexist')).to be true
  end
end