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Testing Container Filter Implementation in devdocs

This test suite validates the ContainerFilter functionality in the devdocs documentation system, focusing on HTML element selection and container handling. It ensures proper extraction and processing of content based on CSS selectors and dynamic container configurations.

Test Coverage Overview

The test suite provides comprehensive coverage of container filtering scenarios:

CSS selector-based container identification
Dynamic container selection via block execution
Fallback behavior for nil containers
HTML fragment vs. full document handling

Implementation Analysis

The testing approach utilizes Minitest’s spec-style syntax with context-based organization. It implements the FilterTestHelper module for shared functionality and employs before blocks for test setup. The tests validate both successful cases and error conditions using assertions and exception handling.

Technical Details

Testing infrastructure includes:

Minitest as the testing framework
Custom FilterTestHelper module
Mock HTML content for testing
ContainerFilter class integration
Dynamic context configuration

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test contexts
Clear arrangement of test scenarios
Proper error handling validation
Comprehensive edge case coverage
Modular test organization

freecodecamp/devdocs

test/lib/docs/filters/core/container_test.rb

            
require_relative '../../../../test_helper'
require_relative '../../../../../lib/docs'

class ContainerFilterTest < Minitest::Spec
  include FilterTestHelper
  self.filter_class = Docs::ContainerFilter
  self.filter_type = 'html'

  before do
    @body = '<div>Test</div>'
  end

  context "when context[:container] is a CSS selector" do
    before { context[:container] = '.main' }

    it "returns the element when it exists" do
      @body = '<div><div class="main">Main</div></div><div></div>'
      assert_equal 'Main', filter_output.inner_html
    end

    it "raises an error when the element doesn't exist" do
      assert_raises Docs::ContainerFilter::ContainerNotFound do
        filter.call
      end
    end
  end

  context "when context[:container] is a block" do
    it "calls the block with itself" do
      context[:container] = ->(arg) { @arg = arg; nil }
      filter.call
      assert_equal filter, @arg
    end

    context "and the block returns a CSS selector" do
      before { context[:container] = ->(_) { '.main' } }

      it "returns the element when it exists" do
        @body = '<div><div class="main">Main</div></div>'
        assert_equal 'Main', filter_output.inner_html
      end

      it "raises an error when the element doesn't exist" do
        assert_raises Docs::ContainerFilter::ContainerNotFound do
          filter.call
        end
      end
    end

    context "and the block returns nil" do
      before { context[:container] = ->(_) { nil } }

      it "returns the document" do
        assert_equal @body, filter_output.inner_html
      end
    end
  end

  context "when context[:container] is nil" do
    context "and the document is an HTML fragment" do
      it "returns the document" do
        assert_equal @body, filter_output.inner_html
      end
    end

    context "and the document is an HTML document" do
      it "returns the <body>" do
        @body = '<html><meta charset=utf-8><title></title><div>Test</div></html>'
        assert_equal '<div>Test</div>', filter_output.inner_html
      end
    end
  end
end