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Testing Error Middleware Response Handling in ruby-grape/grape

This test suite validates the error handling middleware functionality in the Grape framework. It focuses on testing various error response scenarios, status codes, and message handling to ensure robust error management.

Test Coverage Overview

The test suite provides comprehensive coverage of Grape’s error middleware functionality, including:

Status code handling and validation
Custom error message processing
Default error states and messages
HTTP code integration

Implementation Analysis

The testing approach utilizes RSpec’s behavior-driven development patterns to validate error middleware behavior. It implements a mock application setup using Rack::Builder and employs custom error entity classes for structured error responses.

Key patterns include:

Class-level error state management
Dynamic middleware configuration
Entity-based error formatting

Technical Details

Testing infrastructure includes:

RSpec testing framework
Rack::Builder for middleware setup
Grape::Entity for error response formatting
Custom EndpointFaker support class
Mock application implementation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test scenarios using let blocks
Clear separation of setup and assertions
Comprehensive edge case coverage
Consistent error response validation
Modular test organization

ruby-grape/grape

spec/grape/middleware/error_spec.rb

            
# frozen_string_literal: true

describe Grape::Middleware::Error do
  let(:error_entity) do
    Class.new(Grape::Entity) do
      expose :code
      expose :static

      def static
        'static text'
      end
    end
  end
  let(:err_app) do
    Class.new do
      class << self
        attr_accessor :error, :format

        def call(_env)
          throw :error, error
        end
      end
    end
  end
  let(:options) { { default_message: 'Aww, hamburgers.' } }

  let(:app) do
    opts = options
    context = self
    Rack::Builder.app do
      use Spec::Support::EndpointFaker
      use Grape::Middleware::Error, opts # rubocop:disable RSpec/DescribedClass
      run context.err_app
    end
  end

  it 'sets the status code appropriately' do
    err_app.error = { status: 410 }
    get '/'
    expect(last_response.status).to eq(410)
  end

  it 'sets the status code based on the rack util status code symbol' do
    err_app.error = { status: :gone }
    get '/'
    expect(last_response.status).to eq(410)
  end

  it 'sets the error message appropriately' do
    err_app.error = { message: 'Awesome stuff.' }
    get '/'
    expect(last_response.body).to eq('Awesome stuff.')
  end

  it 'defaults to a 500 status' do
    err_app.error = {}
    get '/'
    expect(last_response).to be_server_error
  end

  it 'has a default message' do
    err_app.error = {}
    get '/'
    expect(last_response.body).to eq('Aww, hamburgers.')
  end

  context 'with http code' do
    let(:options) {  { default_message: 'Aww, hamburgers.' } }

    it 'adds the status code if wanted' do
      err_app.error = { message: { code: 200 } }
      get '/'

      expect(last_response.body).to eq({ code: 200 }.to_json)
    end
  end
end