The introduction of different mocking/stubbing strategies that RR implements is quite refreshing and I can certainly appreciate its terseness. I'm looking forward to your next post and am particularly interested in how RR can be used to stub out instances of unimplemented classes.

How do the last two examples for spec/mocks and flexmock stub out the valid? call on any instance?

Kamal: Thank you. I fixed the code samples.

The mocking needs to happen inside of the block.

What if the method expects a block?

In the example you have mocking and stubbing specifying their return values in the block:

mock(User).find('99') { user } stub(User).find('99') { user1 } stub(User).find { user2 }

but, how would I stub a call to each, select, collect, etc.

array = [1,2] mock(array).select ...?

Blocks have been a pain point for Mocha also, so I'm curious what the RR plan is.

Also, the mocha stubbing example can be done (unless I'm missing some part of the example)

require 'rubygems' require 'mocha' require 'dust' require 'test/unit'

unit_tests do test "changing stub behavior" do User = Class.new User.stubs(:find).with(anything).returns(2) User.stubs(:find).with('99').returns(1) assert_equal 1, User.find('99') assert_equal 2, User.find end end

Sorry, better formatting this time (hopefully):

require 'rubygems'
require 'mocha'
require 'dust'
require 'test/unit'


unit_tests do
  test "changing stub behavior" do
    User = Class.new
    User.stubs(:find).with(anything).returns(2)
    User.stubs(:find).with('99').returns(1)
    assert_equal 1, User.find('99')
    assert_equal 2, User.find
  end
end

Jay: RR provide the yields method. In addition, the return block can also can also take the block convented to a Proc as the last argument (like spec/mocks).

The array is a strange example, because in most situations you can depend on the real implementation for its methods.

Lets say you do want to have something on the yield. Here is an example using yields:

array = [1, 2]
mock.proxy(array).select.yields(2)
return_value = array.select do |value|
  value == 2
end
assert_equal [2], return_value

Of course its limited to one call. It will not iterate. The block only gets called once. This example demonstrates:

array = [1, 2]
mock.proxy(array).select.yields(1)
return_value = array.select do |value|
  value == 2
end
assert_equal [], return_value

You can also use yields to set the return value.

mock(array).select.yields(2) {[2]}

Here is an example using the return value block:

array = [1, 2]
dup_array = array.dup
mock(array).select do |block|
  current_iteration_value = dup_array.shift
  dup_array.select(&block)
end
return_value = array.select do |value|
  value == 2
end
assert_equal [2], return_value

Blocks are tough to mock. What sort of requirements do you have?

Jay: Thanks for the Mocha update. I'll fix the example.

This looks great. Without having known the terminology, I've been wishing that Mocha could setup an expectation that still passed the method call back to the original object. Proxying will definitely come in handy.

Yeah, the all in one line proxying would be handy, but in Mocha specs I've just added one more line aliasing a method before stubbing it, and then returning the call on that, as needed (where the proposed preset reference solution wasn't appropriate). It might not be quite as flexible as true proxying, but since I'm mocking everything out anyways, the fixed values are fine and it's worked well enough when I've needed.

Tammer: Can you provide a code example?

Hello Brian. Today I've updated rails to rev 9248 and rr mocks for dynamic find_by methods in my specs ceased to work, instead giving the message

undefined method find_by_id' for classClass' /usr/lib/ruby/gems/1.8/gems/rr-0.4.8/lib/rr/double_injection.rb:17:in alias_method' /usr/lib/ruby/gems/1.8/gems/rr-0.4.8/lib/rr/double_injection.rb:17:insend' /usr/lib/ruby/gems/1.8/gems/rr-0.4.8/lib/rr/double_injection.rb:17:in `initialize' ....

Could you please look into it ? Sorry if this page isn't appropriate place to report rr bugs, I haven't found links to bugtrackers here.

Thanks, Sergey.

Sergey, thanks for the bug report.

The current bugtracker is at http://rubyforge.org/tracker/?atid=14084&group_id=3656&func=browse

I'll set up a rubyforge project for RR.

Sergey, unfortunately I'm not able to reproduce this issue on Rails 2.1.0. Can you paste your test on http://pastie.caboo.se?

Thanks, Brian

How do I call the actual method (or any method for that matter) on the class I'm trying to stub/mock/proxy?

Example:

` class MyObj def self.meth1; end def self.meth2; end end

mock.proxy(MyObj).meth1 { meth2 } `

Also what if I want to proxy a method but so that the mocked proxy is called FIRST, which would allow me to intercept the call before it's being made. The current mock.proxy() seems to call the original method first and then the proxied code. If I'd want the proxy to be called first, and perhaps decide in the proxy block if the real method should be called or not..how do I do that?

Thanks..

@James: Both use cases are interesting things that I have yet not considered.

The block is not instance_exec'd, so:

mock.proxy(MyObj).meth1 { meth2 }

would not work.

Here is a way to solve it.

mock.proxy(MyObj).meth1 { MyObj.meth2 }

Perhaps it should be instance_exec'd. I'll play around with it.

Regarding the method interception, you could do the following:

original_meth1 = MyObj.method(:meth1)
mock(MyObj).meth1 do
  # do something
  original_meth1.call
end

I'd be willing to add a more explicit hook if a nice api can be found. Maybe something like:

mock.proxy(MyObj).meth1.before {# do something}.after {# This is the return value}

Such a change would be additive, so:

mock.proxy(MyObj).meth1 {# This is the return value}

would still work.

Great library thanks!

Have a bit of a problem, when the unit test in question defines the "teardown" method, none of the RR related assertions work. Is this normal?

For example, the following test "fails" correctly:

class MunnyTest < ActiveSupport::TestCase include RR::Adapters::TestUnit test "testing" do x = Object.new mock(x).to_s { 'foobar' } assert_equal 1,1 end
end

But the following does not (it "passes"):

class MunnyTest < ActiveSupport::TestCase include RR::Adapters::TestUnit

def teardown
  super
end

test "testing" do
  x = Object.new
  mock(x).to_s { 'foobar' }
  assert_equal 1,1
end

end