Add a full stacktrace to doctest tests.

[mateofio]

When you fail a doctest test, the current line is printed. If you reuse a function between tests, it's harder to know which test is failing.

It looks like doctest throws a TestFailureException which is an empty class.

We could add a constructor to this class which calls libunwind if it's compiled in and prints a runtime stack trace.

[Ghabry]

You could also annotate the tests with subcases via DOCTEST_SUBCASE: https://github.com/onqtam/doctest/blob/master/examples/all_features/subcases.cpp

I have a hard time to understand what these unit tests are testing because there is no further explanation anywhere. A stacktrace wouldn't help me alot.

[mateofio]

The sub cases feature doesn't seem to help a lot here. For each test. I'm initializing the data with different values and then animating a move route frame by frame and asserting on the member data each time.

Subcases let you branch, but what I need is parameterized tests. Doctest doesn't yet support parameterized tests.

In order to parameterize this, I'm using function calls. The problem I'm having is that when a test fails, I don't actually know which one it is because the error reported is in the leaf function called by everything.