flexmock-0.4.0.rdoc

Path: doc/releases/flexmock-0.4.0.rdoc
Last Update: Wed Feb 09 10:47:13 +0000 2011

FlexMock 0.4.0 Released

FlexMock is a flexible mocking library for use in Ruby‘s Test::Unit test framework. Version 0.4.0 enhances FlexMock with the ability to stub and mock methods in existing objects.

Changes

New Features in 0.4.0

  • You can now use the flexstub(object) method to mock or stub individual methods in an existing object. The original definitions of the methods are restored at the end of a test.
  • The and_return (and its alias, returns) now accepts a list of arguments and will return the values in the list one at a time for each successive call to the mocked method.
  • The flexmock() method now accepts an initialization block so that a mock can be created and configured in one step without using a local variable. This is really handy when mocking factory or creation methods that in turn return a mock.

What is FlexMock?

FlexMock is a flexible Ruby mocking library that works with Ruby‘s Test::Unit framework to create easy to use mocks.

Features

  • Easy integration with Test::Unit. Mocks created with the flexmock method are automatically verified at the end of the test.
  • A fluent interface that allows mock behavior to be specified very easily.
  • A "record mode" where an existing implementation can record its interaction with a mock for later validation against a new implementation.
  • Easy mocking of individual methods in existing, non-mock objects.

Example

Suppose you had a Dog object that wagged a tail when it was happy. Something like this:

  class Dog
    def initialize(a_tail)
      @tail = a_tail
    end
    def happy
      @tail.wag
    end
  end

To test the Dog class without a real Tail object (perhaps because real Tail objects activate servos in some robotic equipment), you can do something like this:

require ‘test/unit’ require ‘flexmock‘

  class TestDog < Test::Unit::TestCase
    include FlexMock::TestCase

    def test_dog_wags_tail_when_happy
      tail = flexmock("tail")
      tail.should_receive(:wag).once
      dog = Dog.new(tail)
      dog.happy
    end
  end

FlexMock will automatically verify that the mocked tail object received the message wag exactly one time. If it doesn‘t, the test will not pass.

See the FlexMock documentation at onestepback.org/software/flexmock for details on specifying arguments and return values on mocked methods, as well as a simple technique for mocking tail objects when the Dog class creates the tail objects directly.

Availability

FlexMock is distributed with Rails, or you can make sure you have the latest version with a quick RubyGems command:

  gem install flexmock    (you may need root/admin privileges)

Otherwise, you can get it from the more traditional places:

Download:rubyforge.org/project/showfiles.php?group_id=170

You will find documentation at: onestepback.org/software/flexmock/

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