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Validating Method Definition Restrictions in FactoryBot

This test suite validates the behavior of method definitions within FactoryBot factories, specifically focusing on error handling. It ensures that attempting to define methods inside factory blocks raises appropriate error messages, maintaining FactoryBot’s intended usage patterns.

Test Coverage Overview

The test coverage focuses on validating FactoryBot’s error handling when developers attempt to define methods inside factory definitions. It tests:

Method definition restrictions within factory blocks
Error message clarity and specificity
Factory definition validation rules

Implementation Analysis

The testing approach uses RSpec’s expectation syntax to verify error raising behavior. It implements a lambda function containing an invalid factory definition and asserts the specific error type (FactoryBot::MethodDefinitionError) and message content. The test utilizes define_model helper for setting up the test environment.

Technical Details

Testing tools and configuration:

RSpec as the testing framework
FactoryBot for factory definitions
Custom model definition helpers
Lambda functions for error testing
Regular expression matching for error message validation

Best Practices Demonstrated

The test demonstrates several testing best practices:

Isolated test scenarios
Clear error message validation
Proper exception handling testing
Descriptive context and expectation definitions
Clean setup using helper methods

thoughtbot/factory_bot

spec/acceptance/defining_methods_inside_a_factory_spec.rb

            
describe "defining methods inside FactoryBot" do
  it "raises with a meaningful message" do
    define_model("User")

    bad_factory_definition = -> do
      FactoryBot.define do
        factory :user do
          def generate_name
            "John Doe"
          end
        end
      end
    end

    expect(&bad_factory_definition).to raise_error(
      FactoryBot::MethodDefinitionError,
      /Defining methods in blocks \(trait or factory\) is not supported \(generate_name\)/
    )
  end
end