flexmock-0.5.0.rdoc

Path: doc/releases/flexmock-0.5.0.rdoc
Last Update: Wed Feb 09 10:47:13 +0000 2011

FlexMock 0.5.0 Released

FlexMock is a flexible mocking library for use in Ruby‘s Test::Unit test framework. Version 0.5.0 adds the ability to automatically stub any instance created by an existing class.

New in 0.5.0

  • flexstub(obj) will now accept a block argument in the same way that flexmock() does.
  • When stubbing Class objects, the any_instance method can be used to automatically stub any instance object created by the class. For example, if you wish that any Connection object created during a test has a stubbed "send" method, you could do the following:
        def test_connections
          flexstub(Connection).any_instance do |new_con|
            new_con.should_receive(:send).and_return(0)
          end
          connection = Connection.new
          connection.send    # This calls the stubbed version of send.
        end
    

    Only objects created during the test will be automatically stubbed. Existing objects are unaffected.

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

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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