Posted by James Mead
Thu, 31 Aug 2006 04:25:00 GMT
It’s great to see that Gluttonous has been playing with Mocha. Like many people, he’s found the ability to mock or stub class methods particularly useful – and this is one of the key differentiators between Mocha and other Ruby mocking libraries.
He’s been trying to improve the test coverage for Rails and submitted this patch where there is an interesting discussion1 about why he would prefer to use Mocha. Interestingly, there has also been some recent discussion on the RSpec mailing list about adding Mocha-like functionality.
On a different note, in his article Mocks for Speed, Gluttonous draws attention to one of the advantages I have previously mentioned of using mocks extensively to write unit tests that test a class in isolation – namely a fast build.
1 We have now released Mocha under the MIT license so it can be used for testing within Rails.
Tags class, fixture, instance, method, mock, mocking, rails, ruby, stub, stubbing, test, testing | 4 comments
Posted by James Mead
Sun, 16 Jul 2006 19:01:00 GMT
Again – I’m not really very pleased with this example, but hopefully it makes some sense. It’s important to realise that the test is not running in a normal Rails environment with the standard auto-require. In fact the first time the Comment class is encountered AutoMocha uses const_missing to supply a Mocha::Mock in its place. From that point on – any further references get the same mock object.
class Article
attr_reader :id
def accepted_comments
Comment.find_all_by_article_id(self.id).select { |comment| comment.accepted? }
end
end
require 'rubygems'
require 'auto_mocha'
require 'test/unit'
class OrderTest < Test::Unit::TestCase
include Mocha
def test_should_return_accepted_comments_for_this_article
unaccepted_comment = Mock.new(:accepted? => false)
accepted_comment = Mock.new(:accepted? => true)
comments = [unaccepted_comment, accepted_comment]
Comment.stubs(:find_all_by_article_id).returns(comments)
article = Article.new
assert_equal [accepted_comment], article.accepted_comments
end
end
Tags class, dependency, expectation, method, mock, mocking, rails, ruby, stub, stubbing, test, testing | no comments
Posted by James Mead
Sun, 16 Jul 2006 19:00:00 GMT
I don’t really like this example, but it’s the best I’ve got at the moment. The any_instance bit is particularly contrived, but hopefully you get the idea.
class Order
attr_accessor :shipped_on
def total_cost
line_items.inject(0) { |total, line_item| total + line_item.price } + shipping_cost
end
def total_weight
line_items.inject(0) { |total, line_item| total + line_item.weight }
end
def shipping_cost
total_weight * 5 + 10
end
class << self
def find_all
end
def number_shipped_since(date)
find_all.select { |order| order.shipped_on > date }.size
end
def unshipped_value
find_all.inject(0) { |total, order| order.shipped_on ? total : total + order.total_cost }
end
end
end
require 'rubygems'
require 'stubba'
require 'test/unit'
class OrderTest < Test::Unit::TestCase
def test_should_calculate_shipping_cost_based_on_total_weight
order = Order.new
order.stubs(:total_weight).returns(10)
assert_equal 60, order.shipping_cost
end
def test_should_count_number_of_orders_shipped_after_specified_date
now = Time.now; week_in_secs = 7 * 24 * 60 * 60
order_1 = Order.new; order_1.shipped_on = now - 1 * week_in_secs
order_2 = Order.new; order_2.shipped_on = now - 3 * week_in_secs
Order.stubs(:find_all).returns([order_1, order_2])
assert_equal 1, Order.number_shipped_since(now - 2 * week_in_secs)
end
def test_should_calculate_value_of_unshipped_orders
Order.stubs(:find_all).returns([Order.new, Order.new, Order.new])
Order.any_instance.stubs(:shipped_on).returns(nil)
Order.any_instance.stubs(:total_cost).returns(10)
assert_equal 30, Order.unshipped_value
end
end
Tags class, expectation, method, mock, mocking, ruby, stub, stubbing, test, testing | no comments
Posted by James Mead
Sun, 16 Jul 2006 18:59:00 GMT
I thought I’d put the examples from the RDoc README up here if only for the syntax highlighting.
class Enterprise
def initialize(dilithium)
@dilithium = dilithium
end
def go(warp_factor)
warp_factor.times { @dilithium.nuke(:anti_matter) }
end
end
require 'rubygems'
require 'mocha'
require 'test/unit'
class EnterpriseTest < Test::Unit::TestCase
include Mocha
def test_should_boldly_go
dilithium = Mock.new
dilithium.expects(:nuke).with(:anti_matter).at_least_once
enterprise = Enterprise.new(dilithium)
enterprise.go(2)
dilithium.verify
end
end
Tags expectation, instance, method, mock, mocking, ruby, stub, stubbing, test, testing | no comments
