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Testing Nested Helper Method Inheritance in Grape API

This test suite examines the behavior of nested helpers in Grape API, focusing on helper method accessibility across different resource levels. It verifies that helper methods defined at one level are properly accessible throughout nested resource hierarchies.

Test Coverage Overview

The test suite provides comprehensive coverage of Grape API’s helper method inheritance and accessibility.

Key areas tested include:

Helper method access in mounted resources
Helper method availability in nested resource levels
Current user context preservation across resource levels
Module-based helper method implementation

Implementation Analysis

The testing approach uses RSpec to create dynamic test scenarios with nested API resources.

Implementation highlights:

Dynamic class creation using Class.new(Grape::API)
Module extension with Grape::API::Helpers
Resource nesting using multiple levels (level1/level2)
Context preservation using let blocks

Technical Details

Testing infrastructure includes:

RSpec testing framework
Grape API framework
Helper method module extension
HTTP GET request simulation
Response body validation
Dynamic context management

Best Practices Demonstrated

The test suite exemplifies several testing best practices in API development:

Isolation of helper methods in separate modules
Clean separation of concerns between resources
Proper use of RSpec context and let blocks
Clear test case organization
Effective use of dynamic class generation for testing

ruby-grape/grape

spec/grape/api/nested_helpers_spec.rb

            
# frozen_string_literal: true

describe Grape::API::Helpers do
  let(:helper_methods) do
    Module.new do
      extend Grape::API::Helpers
      def current_user
        @current_user ||= params[:current_user]
      end
    end
  end
  let(:nested) do
    context = self

    Class.new(Grape::API) do
      resource :level1 do
        helpers context.helper_methods

        get do
          current_user
        end

        resource :level2 do
          get do
            current_user
          end
        end
      end
    end
  end
  let(:main) do
    context = self

    Class.new(Grape::API) do
      mount context.nested
    end
  end

  def app
    main
  end

  it 'can access helpers from a mounted resource' do
    get '/level1', current_user: 'hello'
    expect(last_response.body).to eq('hello')
  end

  it 'can access helpers from a mounted resource in a nested resource' do
    get '/level1/level2', current_user: 'world'
    expect(last_response.body).to eq('world')
  end
end