mocha developer - Jul 2007 - Problem with Mocks: "random" tests failing

Hi all!

I am pretty new to Mocha and I am writing tests that use Mocks quite a bit.
I am having a weird behavior with some of the tests for a specific class:

I wrote a first couple of tests that were passing and then when adding a 3rd
one, the first tests begun to fail. Now what''s bugging me even more is
that
if I run them in debugger mode with breakpoints on the functions where the
errors are, they either pass or fail on other expectations.

A few more interesting things are:
- These tests all use pretty much the same functions
- The class under test launches threads and some of the expectations are
within the threads
- Only expectations fail like this (all assert always pass)
- Commenting "random" lines (like removing an expect on no errors
should be
logged) can change the outcome of the tests

So it looks like either I''m not doing the proper setup/teardown actions
or
the threads are posing a problem. In my setup I always reload (require) all
the libraries I need, and create fresh objects. In the teardown I get rid of
the objects under test.

I am using the mocha gem 0.5.1 and these problems are really driving me
craaaaazy!

Please let me know if you ohave any hints for me! I''ll be happy to give
more
information if required.

Thanks alot,
Laurent

On 7/9/07, Laurent Francioli <laurent.francioli at gmail.com>
wrote:
> Hi all!
>
> I am pretty new to Mocha and I am writing tests that use Mocks quite a bit.
> I am having a weird behavior with some of the tests for a specific class:
>
> I wrote a first couple of tests that were passing and then when adding a
3rd
> one, the first tests begun to fail. Now what''s bugging me even
more is that
> if I run them in debugger mode with breakpoints on the functions where the
> errors are, they either pass or fail on other expectations.
>
> A few more interesting things are:
> - These tests all use pretty much the same functions
> - The class under test launches threads and some of the expectations are
> within the threads
> - Only expectations fail like this (all assert always pass)
> - Commenting "random" lines (like removing an expect on no errors
should be
> logged) can change the outcome of the tests
>
> So it looks like either I''m not doing the proper setup/teardown
actions or
> the threads are posing a problem. In my setup I always reload (require) all
> the libraries I need, and create fresh objects. In the teardown I get rid
of
> the objects under test.
>
> I am using the mocha gem 0.5.1 and these problems are really driving me
> craaaaazy!
>
> Please let me know if you ohave any hints for me! I''ll be happy to
give more
> information if required.
I think we''d really need specific examples to be able to help you. Is
it possible for you to post the code? Both the test code and the code
being tested would be most helpful.
>
> Thanks alot,
> Laurent
> _______________________________________________
> mocha-developer mailing list
> mocha-developer at rubyforge.org
> http://rubyforge.org/mailman/listinfo/mocha-developer
>

I suspect this is due to the fact that exceptions raised in one thread
are not caught in another. Mocha was not designed to test across
multiple threads. In general it is not a good idea to do
multi-threaded unit testing.

You need to separate out the multi-threaded concern of the code so you
can unit test the logic in a single thread. There is an excellent
article on the JMock site (http://www.jmock.org/threads.html) that
should explain this better - don''t be put off by the fact the examples
are in Java - they are very readable.

If you are still stuck - perhaps you can do as David suggests and send
us a chunk of sample code that you are having difficulty testing.
-- 
James.
http://blog.floehopper.org