tests: add check_unittests helper function

[aabadie]

Contribution description

This PR introduces the check_unittests helper function and make use of it with tests using the embUnit module.
For these tests all testfunc are almost the same, so this PR removes a lot of duplication. check_unittests also takes an nb_tests parameter to specify the expected number of successful tests. If the parameter is not set, the default regexp \d+ is used.

All candidate tests are updated to make use of this new function.

Testing procedure

A green Murdock with CI: run tests label set

Issues/PRs references

None

[aabadie]

All tests are passing except this one which is unrelated.

[miri64]

In general, good idea, but there is room for improvement IMHO.

[aabadie]

Thanks for the review and suggestion @miri64. I adapted the PR and the tests I think you talking about. In the meantime, I slightly reworked the script of some package tests.

[miri64]

Except for the error pointed out by Murdock (and me above) this looks good now. Please squash.

[miri64]

ACK. Consolidating similar functionality to a common test absolutely makes sense. If something is broken, Murdock will figure that out.

[miri64]

Only thing to consider is, if the placement of the function within the module is best considering #10949.

[aabadie]

if the placement of the function within the module is best considering

Looking at #10949 and there will be some adaption required but that doesn't seem like a big problem. Regarding the placement, I would say that it helps.