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Testing API Remounting and Dynamic Configuration in ruby-grape/grape

This test suite examines the API remounting capabilities in the Grape framework, focusing on dynamic configurations and endpoint mounting behaviors. It validates how APIs can be remounted with different configurations and ensures proper route handling across multiple mounting scenarios.
Test Coverage Overview

The test suite provides comprehensive coverage of API remounting functionality in Grape:
Basic route mounting with single and multiple instances
Namespace-based mounting scenarios
Dynamic configuration handling
Conditional endpoint mounting
Parameter validation and configuration
Complex nested API scenarios
Implementation Analysis

The testing approach utilizes RSpec’s behavior-driven development patterns to validate API remounting:
Context-based test organization for different mounting scenarios
Dynamic configuration testing using mounted blocks
Helper method validation with configuration access
Complex nested API validation with conditional mounting
Technical Details

Key technical components include:
RSpec test framework
Grape API framework
Shared versioning examples
Dynamic configuration blocks
Route parameter validation
Response status verification
Best Practices Demonstrated

The test suite exemplifies several testing best practices:
Isolated test contexts for different scenarios
Comprehensive edge case coverage
Clear test organization and structure
Effective use of before blocks for setup
Proper response validation
Dynamic configuration testing patterns
ruby-grape/grape

spec/grape/api_remount_spec.rb
            
# frozen_string_literal: true

require 'shared/versioning_examples'

describe Grape::API do
  subject(:a_remounted_api) { Class.new(described_class) }

  let(:root_api) { Class.new(described_class) }

  let(:app) { root_api }

  describe 'remounting an API' do
    context 'with a defined route' do
      before do
        a_remounted_api.get '/votes' do
          '10 votes'
        end
      end

      context 'when mounting one instance' do
        before do
          root_api.mount a_remounted_api
        end

        it 'can access the endpoint' do
          get '/votes'
          expect(last_response.body).to eql '10 votes'
        end
      end

      context 'when mounting twice' do
        before do
          root_api.mount a_remounted_api => '/posts'
          root_api.mount a_remounted_api => '/comments'
        end

        it 'can access the votes in both places' do
          get '/posts/votes'
          expect(last_response.body).to eql '10 votes'
          get '/comments/votes'
          expect(last_response.body).to eql '10 votes'
        end
      end

      context 'when mounting on namespace' do
        before do
          stub_const('StaticRefToAPI', a_remounted_api)
          root_api.namespace 'posts' do
            mount StaticRefToAPI
          end

          root_api.namespace 'comments' do
            mount StaticRefToAPI
          end
        end

        it 'can access the votes in both places' do
          get '/posts/votes'
          expect(last_response.body).to eql '10 votes'
          get '/comments/votes'
          expect(last_response.body).to eql '10 votes'
        end
      end
    end

    describe 'with dynamic configuration' do
      context 'when mounting an endpoint conditional on a configuration' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            get 'always' do
              'success'
            end

            given configuration[:mount_sometimes] do
              get 'sometimes' do
                'sometimes'
              end
            end
          end
        end

        it 'mounts the endpoints only when configured to do so' do
          root_api.mount({ a_remounted_api => 'with_conditional' }, with: { mount_sometimes: true })
          root_api.mount({ a_remounted_api => 'without_conditional' }, with: { mount_sometimes: false })

          get '/with_conditional/always'
          expect(last_response.body).to eq 'success'

          get '/with_conditional/sometimes'
          expect(last_response.body).to eq 'sometimes'

          get '/without_conditional/always'
          expect(last_response.body).to eq 'success'

          get '/without_conditional/sometimes'
          expect(last_response).to be_not_found
        end
      end

      context 'when using an expression derived from a configuration' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            get(mounted { "api_name_#{configuration[:api_name]}" }) do
              'success'
            end
          end
        end

        before do
          root_api.mount a_remounted_api, with: {
            api_name: 'a_name'
          }
        end

        it 'mounts the endpoint with the name' do
          get 'api_name_a_name'
          expect(last_response.body).to eq 'success'
        end

        it 'does not mount the endpoint with a null name' do
          get 'api_name_'
          expect(last_response.body).not_to eq 'success'
        end

        context 'when the expression lives in a namespace' do
          subject(:a_remounted_api) do
            Class.new(described_class) do
              namespace :base do
                get(mounted { "api_name_#{configuration[:api_name]}" }) do
                  'success'
                end
              end
            end
          end

          it 'mounts the endpoint with the name' do
            get 'base/api_name_a_name'
            expect(last_response.body).to eq 'success'
          end

          it 'does not mount the endpoint with a null name' do
            get 'base/api_name_'
            expect(last_response.body).not_to eq 'success'
          end
        end
      end

      context 'when the params are configured via a configuration' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            params do
              requires configuration[:required_attr_name], type: String
            end

            get(mounted { configuration[:endpoint] }) do
              status 200
            end
          end
        end

        context 'when the configured param is my_attr' do
          it 'requires the configured params' do
            root_api.mount a_remounted_api, with: {
              required_attr_name: 'my_attr',
              endpoint: 'test'
            }
            get 'test?another_attr=1'
            expect(last_response).to be_bad_request
            get 'test?my_attr=1'
            expect(last_response).to be_successful

            root_api.mount a_remounted_api, with: {
              required_attr_name: 'another_attr',
              endpoint: 'test_b'
            }
            get 'test_b?another_attr=1'
            expect(last_response).to be_successful
            get 'test_b?my_attr=1'
            expect(last_response).to be_bad_request
          end
        end
      end

      context 'when executing a standard block within a `mounted` block with all dynamic params' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            mounted do
              desc configuration[:description] do
                headers configuration[:headers]
              end
              get configuration[:endpoint] do
                configuration[:response]
              end
            end
          end
        end

        let(:api_endpoint) { 'custom_endpoint' }
        let(:api_response) { 'custom response' }
        let(:endpoint_description) { 'this is a custom API' }
        let(:headers) do
          {
            'XAuthToken' => {
              'description' => 'Validates your identity',
              'required' => true
            }
          }
        end

        it 'mounts the API and obtains the description and headers definition' do
          root_api.mount a_remounted_api, with: {
            description: endpoint_description,
            headers: headers,
            endpoint: api_endpoint,
            response: api_response
          }
          get api_endpoint
          expect(last_response.body).to eq api_response
          expect(a_remounted_api.instances.last.endpoints.first.options[:route_options][:description])
            .to eq endpoint_description
          expect(a_remounted_api.instances.last.endpoints.first.options[:route_options][:headers])
            .to eq headers
        end
      end

      context 'when executing a custom block on mount' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            get 'always' do
              'success'
            end

            mounted do
              configuration[:endpoints].each do |endpoint_name, endpoint_response|
                get endpoint_name do
                  endpoint_response
                end
              end
            end
          end
        end

        it 'mounts the endpoints only when configured to do so' do
          root_api.mount a_remounted_api, with: { endpoints: { 'api_name' => 'api_response' } }
          get 'api_name'
          expect(last_response.body).to eq 'api_response'
        end
      end

      context 'when the configuration is part of the arguments of a method' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            get configuration[:endpoint_name] do
              'success'
            end
          end
        end

        it 'mounts the endpoint in the location it is configured' do
          root_api.mount a_remounted_api, with: { endpoint_name: 'some_location' }
          get '/some_location'
          expect(last_response.body).to eq 'success'

          get '/different_location'
          expect(last_response).to be_not_found

          root_api.mount a_remounted_api, with: { endpoint_name: 'new_location' }
          get '/new_location'
          expect(last_response.body).to eq 'success'
        end

        context 'when the configuration is the value in a key-arg pair' do
          subject(:a_remounted_api) do
            Class.new(described_class) do
              version 'v1', using: :param, parameter: configuration[:version_param]
              get 'endpoint' do
                'version 1'
              end

              version 'v2', using: :param, parameter: configuration[:version_param]
              get 'endpoint' do
                'version 2'
              end
            end
          end

          it 'takes the param from the configuration' do
            root_api.mount a_remounted_api, with: { version_param: 'param_name' }

            get '/endpoint?param_name=v1'
            expect(last_response.body).to eq 'version 1'

            get '/endpoint?param_name=v2'
            expect(last_response.body).to eq 'version 2'

            get '/endpoint?wrong_param_name=v2'
            expect(last_response.body).to eq 'version 1'
          end
        end
      end

      context 'on the DescSCope' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            desc 'The description of this' do
              tags ['not_configurable_tag', configuration[:a_configurable_tag]]
            end
            get 'location' do
              route.tags
            end
          end
        end

        it 'mounts the endpoint with the appropiate tags' do
          root_api.mount({ a_remounted_api => 'integer' }, with: { a_configurable_tag: 'a configured tag' })
          get '/integer/location', param_key: 'a'
          expect(JSON.parse(last_response.body)).to eq ['not_configurable_tag', 'a configured tag']
        end
      end

      context 'on the ParamScope' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            params do
              requires configuration[:required_param], type: configuration[:required_type]
            end

            get 'location' do
              'success'
            end
          end
        end

        it 'mounts the endpoint in the location it is configured' do
          root_api.mount({ a_remounted_api => 'string' }, with: { required_param: 'param_key', required_type: String })
          root_api.mount({ a_remounted_api => 'integer' }, with: { required_param: 'param_integer', required_type: Integer })

          get '/string/location', param_key: 'a'
          expect(last_response.body).to eq 'success'

          get '/string/location', param_integer: 1
          expect(last_response).to be_bad_request

          get '/integer/location', param_integer: 1
          expect(last_response.body).to eq 'success'

          get '/integer/location', param_integer: 'a'
          expect(last_response).to be_bad_request
        end

        context 'on dynamic checks' do
          subject(:a_remounted_api) do
            Class.new(described_class) do
              params do
                optional :restricted_values, values: -> { [configuration[:allowed_value], 'always'] }
              end

              get 'location' do
                'success'
              end
            end
          end

          it 'can read the configuration on lambdas' do
            root_api.mount a_remounted_api, with: { allowed_value: 'sometimes' }
            get '/location', restricted_values: 'always'
            expect(last_response.body).to eq 'success'
            get '/location', restricted_values: 'sometimes'
            expect(last_response.body).to eq 'success'
            get '/location', restricted_values: 'never'
            expect(last_response).to be_bad_request
          end
        end
      end

      context 'when the configuration is read within a namespace' do
        before do
          a_remounted_api.namespace 'api' do
            params do
              requires configuration[:required_param]
            end
            get "/#{configuration[:path]}" do
              '10 votes'
            end
          end
          root_api.mount a_remounted_api, with: { path: 'votes', required_param: 'param_key' }
          root_api.mount a_remounted_api, with: { path: 'scores', required_param: 'param_key' }
        end

        it 'uses the dynamic configuration on all routes' do
          get 'api/votes', param_key: 'a'
          expect(last_response.body).to eql '10 votes'
          get 'api/scores', param_key: 'a'
          expect(last_response.body).to eql '10 votes'
          get 'api/votes'
          expect(last_response).to be_bad_request
        end
      end

      context 'a very complex configuration example' do
        before do
          top_level_api = Class.new(described_class) do
            remounted_api = Class.new(Grape::API) do
              get configuration[:endpoint_name] do
                configuration[:response]
              end
            end

            expression_namespace = mounted { configuration[:namespace].to_s * 2 }
            given(mounted { configuration[:should_mount_expressed] != false }) do
              namespace expression_namespace do
                mount remounted_api, with: { endpoint_name: configuration[:endpoint_name], response: configuration[:endpoint_response] }
              end
            end
          end
          root_api.mount top_level_api, with: configuration_options
        end

        context 'when the namespace should be mounted' do
          let(:configuration_options) do
            {
              should_mount_expressed: true,
              namespace: 'bang',
              endpoint_name: 'james',
              endpoint_response: 'bond'
            }
          end

          it 'gets a response' do
            get 'bangbang/james'
            expect(last_response.body).to eq 'bond'
          end
        end

        context 'when should be mounted is nil' do
          let(:configuration_options) do
            {
              should_mount_expressed: nil,
              namespace: 'bang',
              endpoint_name: 'james',
              endpoint_response: 'bond'
            }
          end

          it 'gets a response' do
            get 'bangbang/james'
            expect(last_response.body).to eq 'bond'
          end
        end

        context 'when it should not be mounted' do
          let(:configuration_options) do
            {
              should_mount_expressed: false,
              namespace: 'bang',
              endpoint_name: 'james',
              endpoint_response: 'bond'
            }
          end

          it 'gets a response' do
            get 'bangbang/james'
            expect(last_response.body).not_to eq 'bond'
          end
        end
      end

      context 'when the configuration is read in a helper' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            helpers do
              def printed_response
                configuration[:some_value]
              end
            end

            get 'location' do
              printed_response
            end
          end
        end

        it 'uses the dynamic configuration on all routes' do
          root_api.mount(a_remounted_api, with: { some_value: 'response value' })

          get '/location'
          expect(last_response.body).to eq 'response value'
        end
      end

      context 'when the configuration is read within the response block' do
        subject(:a_remounted_api) do
          Class.new(described_class) do
            get 'location' do
              configuration[:some_value]
            end
          end
        end

        it 'uses the dynamic configuration on all routes' do
          root_api.mount(a_remounted_api, with: { some_value: 'response value' })

          get '/location'
          expect(last_response.body).to eq 'response value'
        end
      end
    end
  end
end