Floehopper: Tag mocha

Mocha Release 0.9.1

James Mead — Sat, 30 Aug 2008 16:48:00 +0000

Release Notes

Fixed bug #21465 – expects & stubs should support method names as strings (as well as symbols) or fail fast. Convert all expectation method names to a symbol in case they were supplied as a string.
By removing Mock#unexpected_method_called we reduce the number of methods vulnerable to the problem that surfaced in bug #21563.
Fix bug #21563 – stubbing ‘verified?’ method is unsafe. Instance method names on the Mock class should be more obscure.
Performance improvement. StubbaExampleTest goes twice as fast on my local machine.
Added primitive performance test to default rake task.
Fix format of case statements which don’t work in Ruby 1.9 and make others consistent.
There is no point in running (potentially expensive) checks if configuration is set to allow such checks to fail. This is a relatively quick fix in response to Chris McGrath’s performance problems.
Fix for bug #21161 – ‘uninitialized constant Deprecation in stubba.rb’.
It’s more readable to talk about ‘once’ and ‘twice’ rather than ‘1 time’ and ‘2 times’.
Fix bug #20883 – never should raise when called to prevent follow up errors. Fail fast when there are no matching invokable expectations and handle the stub_everything case sensibly. This might not be entirely backwards compatible, but I think the benefits outweigh the risks. The most likely change is that a test that was already failing will now fail faster, which doesn’t seem so awful.

Optional Parameters in Mocha

James Mead — Sat, 12 Jul 2008 11:30:03 +0000

One of the new features added in Mocha 0.9 is the ability to specify the values of optional parameters without requiring them to be present. Some examples should make this clearer…

Let’s assume we’re trying to set up an expectation for the invocation of a method which has some parameters with default values…

  def my_method(one, two, three = 3, four = 4)
    # implementation
  end

We can use the new Mocha::ParameterMatchers#optionally method within the call to Expectation#with as follows…

  object = mock('object')
  object.expects(:my_method).with(1, 2, optionally(3, 4))

This specifies that we are expecting an invocation of my_method. As usual, the first two required parameters (one & two) must have values 1 & 2 respectively. However, the last two optional parameters (three & four) only have to have the values 3 & 4 respectively if they are supplied.

So any of the following invocations would satisfy the expectation…

  object.my_method(1, 2)
  object.my_method(1, 2, 3)
  object.my_method(1, 2, 3, 4)

Whereas none of the following invocations would satisfy the expectation and an error would be raised…

  object.my_method(1)
  object.my_method(1, 3)
  object.my_method(1, 2, 4)
  object.my_method(1, 2, 4, 4)
  object.my_method(1, 2, 3, 5)

Mocha 0.9 Released

James Mead — Tue, 24 Jun 2008 19:14:00 +0000

There’s been quite a bit of work going on in Mocha over recent months, but a release is long overdue. The API is now pretty stable and so this release jumps from version 0.5 to 0.9. Much of the work has been refactoring Mocha’s internals to support new features and make the code more maintainable.

Before attempting the refactoring, extensive acceptance tests were added. One of the benefits of this is that it should now be easier to write new acceptance tests if you want to suggest new features or illustrate a bug ;-)

Here’s a quick summary of the changes in the release. I’ll try to post some code examples here in the near future.

Ordering constraints

Based on the JMock constraints with the same names…

Added “sequences” for constraining the order of expected invocations. See Standalone#sequence and Expectation#in_sequence.
Added “states” for constraining the order of expected invocations. See Standalone#states, Expectation#then, Expectation#when and StateMachine.

Configurable warnings or errors

When a method on a non-public method is stubbed
When a method on a non-existent method is stubbed
When a method on a non-mock object is stubbed (partial mocking)
When a method is stubbed unnecessarily (i.e. the stubbed method is not called during the test)

See Configuration for more details.

Improved error messages

A more readable and complete list of unsatisfied expectations, satisfied expectations and state machines.
Display more sensible failure message for any_instance expectations.

Parameter matchers

New to this release: optionally (allows matching of optional parameters if available), yaml_equivalent (allows matching of YAML that represents the specified object), responds_with (tests the quack not the duck).
Nesting of matchers is now supported.

Syntax shortcut

An optional block can be passed into the Standalone#mock method. The block is evaluated in the context of the new mock instance and can be used as a shortcut to set up expectations.

Ruby & Rails compatibility

Tested with Ruby 1.8.4, 1.8.5, 1.8.6 & 1.9. All related bugs and warnings believed to be fixed.

Tested with Rails 1.2.3 & Rails 2.1.0.

Deprecation

There is no longer any need to have a “require ‘stubba’” statement in your code. A deprecation warning has been added to this effect, because the file will be removed in a future release.

Bug fixes

Mocha Mailing List Move

James Mead — Thu, 19 Jun 2008 20:32:38 +0000

The Mocha Mailing List has moved to Google Groups.

Group name: mocha-developer
Group home page: http://groups.google.com/group/mocha-developer
Group email address mocha-developer@googlegroups.com

Mocking in Java using Mocha

James Mead — Sun, 17 Feb 2008 18:10:01 +0000

Ola Bini one of the JRuby guys has released the JtestR tool which allows you to write tests for Java code in Ruby! Ola has bundled a number of Ruby libraries – Mocha, RSpec, Dust, Test::Unit & ActiveSupport – together with JRuby to allow you to write Ruby test cases that test Java code.

He has a couple of examples in the Mock documentation of how to use Mocha...

The first one demonstrates using Mocha to mock an interface (Map).

  import java.util.Map
  import java.util.Iterator
  import java.util.Set
  import java.util.HashMap

  functional_tests do 
    test "that a new HashMap can be created based on another map" do 
      map = Map.new

      map.expects(:size).returns(0)

      iter = Iterator.new
      iter.expects(:hasNext).returns(false)

      set = Set.new
      set.expects(:iterator).returns(iter)

      map.expects(:entrySet).returns(set)

      assert_equals 0, HashMap.new(map).size
    end
  end

The second example demonstrates using Mocha to setup expectations on a real (non-mock) instance (HashMap)...

  import java.util.Iterator
  import java.util.Set
  import java.util.HashMap

  functional_tests do 
    test "that a new HashMap can be created based on another map" do 
      map = mock(HashMap)

      map.expects(:size).returns(0)

      iter = Iterator.new
      iter.expects(:hasNext).returns(false)

      set = Set.new
      set.expects(:iterator).returns(iter)

      map.expects(:entrySet).returns(set)

      assert_equals 0, HashMap.new(map).size
    end
  end

Mock Commands, Stub Queries

James Mead — Fri, 03 Aug 2007 10:10:00 +0000

Zach Moazeni has just posted a suggested patch for Mocha over on his blog. My understanding of the patch is that it means expectations are verified even when an assertion error occurs in the test. Here is his example…


  class Car

    def initialize(parts = [])
      @parts = parts
    end

    def start
      started = true
      @parts.each do | part |
        # commenting out for failure
        # started = started && part.start
      end

      started
    end

  end

  class SomeTest < Test::Unit::TestCase

    def test_start
      engine_mock = mock("engine_mock")
      car = Car.new([engine_mock])

      engine_mock.expects(:start).returns(false)
      assert !car.start
    end

  end

I’ve had a friendly & useful conversation with Zach about it, but I’m not convinced this is the right way to go. Using the one assertion per test school of thought, you can achieve the same goal by splitting the test into two so you get a test failure for the expectation and another for the assertion…


  class SomeTest < Test::Unit::TestCase

    def test_should_start_engine
      engine = mock('engine')
      car = Car.new([engine])

      engine.expects(:start)

      car.start
    end

    def test_should_start_if_engine_starts
      engine = stub('engine')
      car = Car.new([engine])

      engine.stubs(:start).returns(false)

      assert !car.start
    end

  end

Something that makes the example less suitable for mocking is that the Car#start method is both a command and a query. If you separate the two, testing with mocks might be easier…


  class Car

    def initialize(parts = [])
      @parts = parts
    end

    def start
      @parts.each { |part| part.start }
    end

    def started?
      @parts.all? { |part| part.started? }
    end

  end

  class SomeOtherTest < Test::Unit::TestCase

    def test_should_start_engine
      engine = mock('engine')
      car = Car.new([engine])

      engine.expects(:start)

      car.start
    end

    def test_should_not_be_started_if_engine_is_started
      engine = stub('engine')
      car = Car.new([engine])

      engine.stubs(:started?).returns(false)

      assert !car.started?
    end

  end

I’d be interested to know what other people think…

One thing I do agree with Zach about is that submitting a suggested patch to an open source project is a great way of initiating a constructive conversation.

Mock Objects in Ruby

James Mead — Sun, 22 Jul 2007 20:48:00 +0000

As promised I’ve finally got round to making the S5 slides of my LRUG talk available here.

You can use various keys to navigate the presentation. If you just want to quickly scan through the content, you might find the outline view useful (press the “T” key to toggle between slideshow & outline modes).

Mocha 0.5 released

James Mead — Fri, 08 Jun 2007 15:46:00 +0000

  sudo gem install mocha

or download one of the latest packages from rubyforge.

Parameter Matchers

I’ve added a few Hamcrest-style parameter matchers which are designed to be used inside Expectation#with. The following matchers are currently available: anything(), includes(), has_key(), has_value(), has_entry(), all_of() & any_of(). More to follow soon. The idea is eventually to get rid of the nasty parameter_block option on Expectation#with.

  object = mock()
  object.expects(:method).with(has_key('key_1'))
  object.method('key_1' => 1, 'key_2' => 2)
  # no verification error raised

  object = mock()
  object.expects(:method).with(has_key('key_1'))
  object.method('key_2' => 2)
  # verification error raised, because method was not called with Hash containing key: 'key_1'

Values Returned and Exceptions Raised on Consecutive Invocations

Allow multiple calls to Expectation#returns and Expectation#raises to build up a sequence of responses to invocations on the mock. Added syntactic sugar method Expectation#then to allow more readable expectations.

  object = mock()
  object.stubs(:method).returns(1, 2).then.raises(Exception).then.returns(4)
  object.method # => 1
  object.method # => 2
  object.method # => raises exception of class Exception
  object.method # => 4

Yields on Consecutive Invocations

Allow multiple calls to yields on single expectation to allow yield parameters to be specified for consecutive invocations.

  object = mock()
  object.stubs(:method).yields(1, 2).then.yields(3)
  object.method { |*values| p values } # => [1, 2]
  object.method { |*values| p values } # => [3]

Multiple Yields on Single Invocation

Added Expectation#multiple_yields to allow a mocked or stubbed method to yield multiple times for a single invocation.

  object = mock()
  object.stubs(:method).multiple_yields([1, 2], [3])
  object.method { |*values| p values } # => [1, 2] # => [3]

Invocation Dispatch

Expectations were already being matched in reverse order i.e. the most recently defined one was being found first. This is still the case, but we now stop matching an expectation when its maximum number of expected invocations is reached. c.f. JMock v1. A stub will never stop matching by default. Hopefully this means we can soon get rid of the need to pass a Proc to Expectation#returns.

  object = mock()
  object.stubs(:method).returns(2)
  object.expects(:method).once.returns(1)
  object.method # => 1
  object.method # => 2
  object.method # => 2
  # no verification error raised

This should still work…

  Time.stubs(:now).returns(Time.parse('Mon Jan 01 00:00:00 UTC 2007'))
  Time.now # => Mon Jan 01 00:00:00 UTC 2007
  Time.stubs(:now).returns(Time.parse('Thu Feb 01 00:00:00 UTC 2007'))
  Time.now # => Thu Feb 01 00:00:00 UTC 2007

Acknowledgements

Thanks to David Chelimsky, Dan North, Jay Fields, Kevin Clark, Frederick Cheung, James Moore, Brian Helmkamp, Ben Griffiths, Chris Roos & Paul Battley for their input. Apologies to anybody I forgot to mention.

Honourable Mention for Mocha

James Mead — Thu, 10 May 2007 15:15:00 +0000

I just downloaded an updated version of the Pragmatic Bookshelf’s Agile Web Development with Rails book. Maybe it’s been there a while, but I just noticed Mocha is mentioned at the end of the chapter on testing. :-)

Preview of Latest Mocha Changes

James Mead — Thu, 12 Apr 2007 11:57:00 +0000

I’ve finally managed to find some time to do some serious work on Mocha. Here are some code snippets showing the new functionality available in trunk (revision 128). I don’t don’t know how many people out there are using trunk, but it would be great to get some feedback on these changes before I make a new release. In particular I’d like to know whether…

I’ve broken anybody’s tests.
Anybody has a legitimate use for parameter_block in Expectation#with that they don’t think will be handled by a suitable parameter matcher i.e. using the current behaviour where the block is passed the parameters and the result of the block determines whether the expectation matches. I’m planning on deprecating this soon.
Anybody has a legitimate use for passing in an instance of Proc to Expectation#returns i.e. using the current behaviour where the Proc gets executed to generate a return value. I’m planning on deprecating this soon as well.

I’ve typed this up in a bit of a rush (about to go on holiday for a few days), so apologies if there are any mistakes.