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Testing Grape DSL Callback Registration in ruby-grape/grape

This test suite validates the callback functionality in Grape’s DSL module, specifically focusing on before, after, and validation hooks. The tests ensure proper implementation of middleware-style callbacks that are essential for request processing in Grape applications.

Test Coverage Overview

The test suite provides comprehensive coverage of Grape’s callback system, examining four critical middleware hooks: before, before_validation, after_validation, and after. Each callback type is verified to ensure proper registration with the namespace_stackable mechanism.

Tests before hooks for request preprocessing
Validates before_validation callback registration
Confirms after_validation hook implementation
Verifies after hooks for response processing

Implementation Analysis

The testing approach utilizes RSpec’s expect syntax with mock expectations to verify callback registration. The implementation leverages a dummy class that includes the Grape::DSL::Callbacks module, allowing isolated testing of the callback functionality. Each test confirms that the appropriate namespace_stackable method is called with the correct parameters.

The pattern demonstrates proper use of RSpec’s subject and let blocks for clean test organization.

Technical Details

Testing Framework: RSpec
Module Under Test: Grape::DSL::Callbacks
Test Dependencies: Grape DSL module
Mock Objects: Dummy class with included module
Test Pattern: Behavior verification through mock expectations

Best Practices Demonstrated

The test suite exemplifies several testing best practices in Ruby and RSpec. It uses proper isolation through a dummy class, demonstrates clean mock expectations, and maintains single responsibility per test case.

Clear test organization with descriptive contexts
Efficient use of let blocks for setup
Proper module inclusion testing
Consistent testing pattern across related functionality

ruby-grape/grape

spec/grape/dsl/callbacks_spec.rb

            
# frozen_string_literal: true

describe Grape::DSL::Callbacks do
  subject { dummy_class }

  let(:dummy_class) do
    Class.new do
      include Grape::DSL::Callbacks
    end
  end

  let(:proc) { -> {} }

  describe '.before' do
    it 'adds a block to "before"' do
      expect(subject).to receive(:namespace_stackable).with(:befores, proc)
      subject.before(&proc)
    end
  end

  describe '.before_validation' do
    it 'adds a block to "before_validation"' do
      expect(subject).to receive(:namespace_stackable).with(:before_validations, proc)
      subject.before_validation(&proc)
    end
  end

  describe '.after_validation' do
    it 'adds a block to "after_validation"' do
      expect(subject).to receive(:namespace_stackable).with(:after_validations, proc)
      subject.after_validation(&proc)
    end
  end

  describe '.after' do
    it 'adds a block to "after"' do
      expect(subject).to receive(:namespace_stackable).with(:afters, proc)
      subject.after(&proc)
    end
  end
end