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Testing Association Attribute Behavior in factory_bot

This test suite evaluates the Association attribute functionality in FactoryBot, focusing on association creation and handling. It verifies proper association building, name handling, and override application within factory definitions.

Test Coverage Overview

The test suite provides comprehensive coverage of FactoryBot’s Association attribute implementation.

Key areas tested include:

Association attribute instantiation and properties
Association building via proc execution
String-to-symbol name conversion
Override parameter handling

Implementation Analysis

The testing approach uses RSpec’s describe blocks to organize distinct test scenarios for the Association class. It leverages RSpec’s let statements for setup and employs doubles for isolation testing.

Notable patterns include:

Method stubbing with allow/receive
Subject-based testing with RSpec its blocks
Module extension for method definition

Technical Details

Testing tools and setup:

RSpec as the testing framework
Test doubles for association mocking
Dynamic module creation for method definition
Before blocks for test preparation
Subject helper for DRY testing

Best Practices Demonstrated

The test suite exemplifies several testing best practices in Ruby.

Notable practices include:

Isolation of test subjects using doubles
Descriptive context naming
DRY setup using let statements
Focused test cases with single assertions
Clear separation of setup and expectations

thoughtbot/factory_bot

spec/factory_bot/attribute/association_spec.rb

            
describe FactoryBot::Attribute::Association do
  let(:name) { :author }
  let(:factory) { :user }
  let(:overrides) { {first_name: "John"} }
  let(:association) { double("association") }

  subject { FactoryBot::Attribute::Association.new(name, factory, overrides) }

  before do
    # Define an '#association' instance method allowing it to be mocked.
    # Usually this is determined via '#method_missing'
    missing_methods = Module.new {
      def association(*args)
      end
    }
    subject.extend(missing_methods)

    allow(subject)
      .to receive(:association).with(any_args).and_return association
  end

  it { should be_association }
  its(:name) { should eq name }

  it "builds the association when calling the proc" do
    expect(subject.to_proc.call).to eq association
  end

  it "builds the association when calling the proc" do
    subject.to_proc.call
    expect(subject).to have_received(:association).with(factory, overrides)
  end
end

describe FactoryBot::Attribute::Association, "with a string name" do
  subject { FactoryBot::Attribute::Association.new("name", :user, {}) }
  its(:name) { should eq :name }
end