FlexMock 1.1.0 Released

FlexMock is a flexible mocking library for use in unit testing and behavior specification in Ruby. Release 1.1.0 is a minor release with a few bug fixes and some small features.

Changes in 1.1.0

Features

Changes in 1.0.0

Features

Bug Fixes

What is FlexMock?

FlexMock is a flexible framework for creating mock object for testing. When running unit tests, it is often desirable to use isolate the objects being tested from the "real world" by having them interact with simplified test objects. Sometimes these test objects simply return values when called, other times they verify that certain methods were called with particular arguments in a particular order.

FlexMock makes creating these test objects easy.

Features

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:

RSpec.configure do |config|
  config.mock_with :flexmock
end

describe Dog do
  it "wags its tail when happy" do
    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.

Here's the same thing using the new spy support:

describe Dog do
  it "wags its tail when happy" do
    tail = flexmock("tail")
    dog = Dog.new(tail)
    dog.happy
    tail.should have_received(:wag)
  end
end

This style works particularly well with the rspec-given library.

require 'rspec/given'

describe Dog do
  context "when the dog is happy" do
    Given(:tail) { flexmock(:on, Tail) }
    Given(:dog) { Dog.new(tail) }

    When { dog.happy }

    Then { tail.should have_received(:wag) }
  end
end

See the FlexMock documentation at flexmock.rubyforge.org 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)

You will find documentation at: flexmock.rubyforge.org.

-- Jim Weirich