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Mocha is a library for mocking and stubbing using a syntax like that of JMock.

It can be used with many testing frameworks e.g. Test::Unit, RSpec, test/spec, expectations, Dust and even JtestR.

Mocha provides a unified, simple and readable syntax for both traditional mocking and partial mocking.

Mocha was originally harvested from projects at Reevoo by me (James) and my colleagues Ben, Chris and Paul.

Download and Installation

Install the gem with the following command:

$ gem install mocha

Or install the Rails plugin:

$ script/plugin install svn://rubyforge.org/var/svn/mocha/trunk

Using Mocha

require 'test/unit'
require 'rubygems'
require 'mocha'

class ExampleTest < Test::Unit::TestCase

  def test_mocking_a_class_method
    product = Product.new
    Product.expects(:find).with(1).returns(product)
    assert_equal product, Product.find(1)
  end

  def test_mocking_an_instance_method_on_a_real_object
    product = Product.new
    product.expects(:save).returns(true)
    assert product.save
  end

  def test_stubbing_instance_methods_on_real_objects
    prices = [stub(:pence => 1000), stub(:pence => 2000)]
    product = Product.new
    product.stubs(:prices).returns(prices)
    assert_equal [1000, 2000], product.prices.collect {|p| p.pence}
  end

  def test_stubbing_an_instance_method_on_all_instances_of_a_class
    Product.any_instance.stubs(:name).returns('stubbed_name')
    product = Product.new
    assert_equal 'stubbed_name', product.name
  end

  def test_traditional_mocking
    object = mock()
    object.expects(:expected_method).with(:p1, :p2).returns(:result)
    assert_equal :result, object.expected_method(:p1, :p2)
  end

  def test_shortcuts
    object = stub(:method1 => :result1, :method2 => :result2)
    assert_equal :result1, object.method1
    assert_equal :result2, object.method2
  end

end

Useful Links

• Documentation
  • Usage Examples
  • Traditional Mocking Example
  • Partial Mocking Example
  • An Introduction to Mock Objects in Ruby (slides from James’ presentation at LRUG)
  • Mocks Aren’t Stubs (by Martin Fowler)

• Mocha on Rubyforge.
  • Bug Reports
  • Feature Requests
  • Patches

• Commits
• Builds
• Rails Plugin
• Mailing List
• Old Mailing List
• Old Mailing List Archive

Licence

You may use, copy and redistribute this library under the same terms as Ruby itself or under the MIT license.