ANN: FlexMock 0.6.0 Released


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= FlexMock 0.6.0 Released

FlexMock is a flexible mocking library for use in unit testing and
behavior specification in Ruby. Version 0.6.0 introduces a number of
API enhancements to make testing with mocks even easier than before.

== New in 0.6.0

  • Better integration with Test::Unit (no need to explicitly include
    FlexMock::TestCase).

  • Integration with RSpec (version 0.9.0 or later of RSpec is required).

  • The +flexmock+ method will now create both regular mocks and partial
    mocks.

    flexmock() # => a full mock
    flexmock(person) # => a partial mock based on person

    (+flexstub+ is still included for backwards compatibility).

  • Quick and simple mocks my now be created using an expectation hash.
    For
    example:

    flexmock(:foo => 10, :bar => “Hello”)

    will create a mock with two methods, :foo and :bar,defined. :foo will
    return 10 when invoked, and :bar will return “Hello”.

  • The +should_receive+ method will now allow multiple methods (with the
    same
    constraints) be defined in a single call. For example, the following
    declares that both :read and :write need to be called at least one
    time each
    on the mock object.

    flexmock.should_receive(:read, :write).at_least.once

  • +should_recieve+ now will allow expectation hashes as arguments. This
    is
    similar to the list of methods, but allows each defined method to have
    its
    own return value.

    flexmock.should_receive(:name => “John”, :age => 32)

  • In addition to using a block for defining constrains, constraints may
    now be
    applied directly to the return value of +new_instances+. Combined with
    the
    expectation hashes supported by +should_receive+, simple mocking
    scenarios
    have become much more succinct. For example:

    flexmock(Person).new_instances.should_receive(:name => "John",
    

:age => 32)

  • Improved implementation, allowing for more flexible use and greater
    consistency between full mock and partial mocks.

  • Version 0.6.0 also includes a fix for an incompatibility with some
    older
    versions of RCov. The FlexMock Rakefile now includes a RCov task (and
    we
    have 100% code coverage).

== 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

  • Easy integration with both Test::Unit and RSpec. Mocks created with
    the
    flexmock method are automatically verified at the end of the test or
    example.

  • 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.

  • The ability to cause classes to instantiate test instances (instead of
    real
    instances) for the duration of a test.

=== 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/test_unit’

class TestDog < Test::Unit::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 http://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)

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

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

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

– Jim W.