Mocha Mock Carries To Another Test

Question

I have been following the 15 TDD steps to create a Rails application guide - but have run into an issue I cannot seem to resolve. For the functional test of the WordsController, I have the following code:

class WordsControllerTest < ActionController::TestCase

  test "should get learn" do
    get 'learn'
    assert_response :success
  end

  test "learn passes a random word" do    
    some_word = Word.new
    Word.expects(:random).returns(some_word)
    get 'learn'
    assert_equal some_word, assigns('word')
  end
end

In the Word class I have the following code:

class Word < ActiveRecord::Base
  def self.random
    all = Word.find :all
    all[rand(all.size)]
  end
end

When I run the tests, I experience the following error (shortened for brevity):

1) Failure: unexpected invocation: Word(...).random() satisfied expectations:
- expected exactly once, already invoked once: Word(...).random()

I have tried changing changing the order of the tests along with a multitude of other things, but time and time again I continue to receive the same test failure - that Word.random() has already been invoked.

I'm running Rails 3.0 beta 4 and Mocha 0.9.8. I've searched long and hard for a solution to my problem, but I can't seem to find it. I'm new to Ruby/Rails so am rather unfamiliar with the language and the frameworks.

Thanks in advance!

Answer 1

I had the same problem, mocked functionality was not isolated to a test, it seems to be a problem with the load order of Mocha.

I had some issues getting Mocha to work with Rails3. I found a few stackoverflow posts regarding, but didn't stumble across the solution until I found a post on agoragames.com

Basically, in the Gemfile of your project, the require for Mocha should look like:

gem 'mocha', :require => false

Then in test/test_helper.rb, add a require line for mocha:

...
...
require File.expand_path('../../config/environment', __FILE__)
require 'rails/test_help'
require 'mocha'

class ActiveSupport::TestCase
...
...

I think the require line for mocha in the Gemfile means that you need to already have mocha installed as a gem, bundler won't take care of it for you.

Answer 2

mocha needs to be loaded last. I struggled a lot with this problem too.

#Gemfile
  group :test
    gem 'mocha', '~>0.9.8', :require => false
    ...
  end

and

test_helper.rb
  ....
  #at the very bottom
  require 'mocha'

Answer 3

Those solutions didn't work for me on their own, using Ruby 2.2.2, Rails 4.2.2, mocha 1.1.0, shoulda-context 1.2.1, factory_girl_rails 4.5.0 and a few more testing related gems.

What did it was also moving these two lines at the bottom of my test_helper.rb:

require 'mocha/setup'
require 'mocha/test_unit'

I also removed require 'test/unit'. It appears that mocha/test_unit already does that for me.

Answer 4

How are you requiring mocha? Are you using bundler? It sounds a bit as if the mocha teardown hook isn't being called?

Answer 5

Additionally, it seems mocha_teardown is not being called with rails31. Mocks that are setup are never removed... (this additional hack fixes it)

  class ActiveSupport::TestCase
    def teardown
      super
      Mocha::Mockery.instance.teardown
      Mocha::Mockery.reset_instance    
    end
  end