Re: [boost] [Polygon] unit tests

Subject: Re: [boost] [Polygon] unit tests
From: Thomas Klimpel (Thomas.Klimpel_at_[hidden])
Date: 2009-09-02 15:22:05

Simonson, Lucanus J wrote:
> Thomas Klimpel wrote:
> > - The unit-tests should be split into smaller files and use a nonzero
> > exit value to indicate failure. They should be placed in
> > libs/polygon/test.
>
> What granularity would you like to see the tests broken into?

It's OK from my point of view to have many tests in a single source file, as long as regression testing is still possible. My basic assumption is that any unit-test can potentially fail, so it's not good if a single failing unit-test will mask many other unrelated test results. The typical reaction in such a situation would be to comment out the failing unit-test, which bears its own risks...

One point to consider when writing unit-tests for a template library is that the compiler will not even find simple typos as long as a template function is not instantiated and called with a concrete type (Try this yourself: Change line 207 of interval_concept.hpp from "high(interval, (newHigh));" to "hhigh(interval, (newHigh));", and see if you can find a compiler that will detect this typo when compiling your current unit-tests.). So I probably would put pure "compile" tests into different source files than real functional tests. Having pure "compile" tests that just exercise every template function in the interface of a concept might be a good idea, especially if the test function is itself a template that is instantiated and called both for a class provided by the library and a custom class which registers as that concept. I also wouldn't object to have "compile" tests for more than one concept in a single source file.

Don't forget the "use a nonzero exit value to indicate failure" advice for the functional tests. Even if you don't want to abort at the first failing test, ensure that the exit value is non-zero as soon as at least one test failed.

> > - Failing unit-tests should not be commented out just because they
> > fail to compile.
>
> I uncommented the handful of tests that I had commented out in the
> unit test source and these tests do compile and pass in MSVC9 and gcc4.2.2.
> The only tests commented out now are one which fails because the
> functionality isn't implemented (planed but not implemented functinality)
> and one that has long runtime and performs no functional testing.

After the custom_xxx.cpp examples failed to compile, I searched for "geometry_concept" in "gtl_boost_unit_test.cpp" and all occurrences of it were in code that was currently commented out. I searched again for "geometry_concept" after your modifications, but the corresponding code is still commented out.

Regards,
Thomas