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Testing Helper Method Inheritance Implementation in ruby-grape/grape

This test suite validates helper method inheritance and overriding behavior in Grape API classes. It ensures proper functionality of inherited helpers across different class hierarchies while verifying parameter validation and error handling.

Test Coverage Overview

The test suite comprehensively covers helper method inheritance patterns in Grape API classes.

Tests inheritance of parameter validation rules
Verifies helper method behavior in non-overriding subclasses
Validates helper method overriding in subclasses
Checks error handling for missing required parameters

Implementation Analysis

The testing approach uses RSpec to create a hierarchical class structure simulating real-world API inheritance scenarios.

It implements multiple test contexts to verify:

Superclass helper method behavior
Subclass method inheritance
Helper method overriding
Parameter validation inheritance

Technical Details

RSpec testing framework
Grape API testing helpers
Dynamic class creation using Class.new
HTTP GET request testing
Response body validation
Parameter validation testing

Best Practices Demonstrated

The test suite exemplifies several testing best practices for API development.

Isolated test contexts for different scenarios
Clear test case organization
Comprehensive edge case coverage
DRY test implementation using shared contexts
Proper setup of test dependencies

ruby-grape/grape

spec/grape/api/inherited_helpers_spec.rb

            
# frozen_string_literal: true

describe Grape::API::Helpers do
  let(:user) { 'Miguel Caneo' }
  let(:id)   { '42' }
  let(:api_super_class) do
    Class.new(Grape::API) do
      helpers do
        params(:superclass_params) { requires :id, type: String }

        def current_user
          params[:user]
        end
      end
    end
  end
  let(:api_overridden_sub_class) do
    Class.new(api_super_class) do
      params { use :superclass_params }

      helpers do
        def current_user
          "#{params[:user]} with id"
        end
      end

      get 'resource' do
        "#{current_user}: #{params['id']}"
      end
    end
  end
  let(:api_sub_class) do
    Class.new(api_super_class) do
      params { use :superclass_params }

      get 'resource' do
        "#{current_user}: #{params['id']}"
      end
    end
  end
  let(:api_example) do
    Class.new(api_sub_class) do
      params { use :superclass_params }

      get 'resource' do
        "#{current_user}: #{params['id']}"
      end
    end
  end

  context 'non overriding subclass' do
    subject { api_sub_class }

    def app
      subject
    end

    context 'given expected params' do
      it 'inherits helpers from a superclass' do
        get '/resource', id: id, user: user
        expect(last_response.body).to eq("#{user}: #{id}")
      end
    end

    context 'with lack of expected params' do
      it 'returns missing error' do
        get '/resource'
        expect(last_response.body).to eq('id is missing')
      end
    end
  end

  context 'overriding subclass' do
    def app
      api_overridden_sub_class
    end

    context 'given expected params' do
      it 'overrides helpers from a superclass' do
        get '/resource', id: id, user: user
        expect(last_response.body).to eq("#{user} with id: #{id}")
      end
    end

    context 'with lack of expected params' do
      it 'returns missing error' do
        get '/resource'
        expect(last_response.body).to eq('id is missing')
      end
    end
  end

  context 'example subclass' do
    def app
      api_example
    end

    context 'given expected params' do
      it 'inherits helpers from a superclass' do
        get '/resource', id: id, user: user
        expect(last_response.body).to eq("#{user}: #{id}")
      end
    end

    context 'with lack of expected params' do
      it 'returns missing error' do
        get '/resource'
        expect(last_response.body).to eq('id is missing')
      end
    end
  end
end