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Testing NullFactory Delegation Patterns in factory_bot

This test suite validates the functionality of the NullFactory class in FactoryBot, focusing on its delegation patterns and attribute behaviors. The tests ensure proper implementation of factory delegation and default attribute handling for null factory instances.

Test Coverage Overview

The test suite provides comprehensive coverage of NullFactory’s core functionality, including:

Delegation behavior for traits, callbacks, attributes, and constructor
Null value handling for compile and class_name attributes
Attribute list instantiation verification
Evaluator class configuration

Implementation Analysis

The testing approach employs RSpec’s delegation matcher to verify proper method forwarding to the definition object. The implementation follows a clear pattern of testing both delegation behavior and direct attribute access, using RSpec’s expectation syntax for precise assertions.

The tests utilize RSpec’s built-in matchers and leverage factory_bot’s internal class structure.

Technical Details

Testing tools and configuration:

RSpec testing framework
FactoryBot test helpers and matchers
Delegation pattern verification
Instance type checking
Nil value validation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Single responsibility principle in test cases
Consistent setup patterns
Clear test descriptions
Proper isolation of test cases
Effective use of RSpec matchers

thoughtbot/factory_bot

spec/factory_bot/null_factory_spec.rb

            
describe FactoryBot::NullFactory do
  it "delegates defined traits to its definition" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory).to delegate(:defined_traits).to(:definition)
  end

  it "delegates callbacks to its definition" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory).to delegate(:callbacks).to(:definition)
  end

  it "delegates attributes to its definition" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory).to delegate(:attributes).to(:definition)
  end

  it "delegates constructor to its definition" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory).to delegate(:constructor).to(:definition)
  end

  it "has a nil value for its compile attribute" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory.compile).to be_nil
  end

  it "has a nil value for its class_name attribute" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory.class_name).to be_nil
  end

  it "has an instance of FactoryBot::AttributeList for its attributes attribute" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory.attributes).to be_an_instance_of(FactoryBot::AttributeList)
  end

  it "has FactoryBot::Evaluator as its evaluator class" do
    null_factory = FactoryBot::NullFactory.new

    expect(null_factory.evaluator_class).to eq FactoryBot::Evaluator
  end
end