Remove obsolete tests/test_assertions.hpp and all references to it

[lukashuebner]

We have multiple (different) redefinitions of KASSERT_KASSERT_HPP_KASSERT_IMPL for testing with KASSERTs. One in tests/test_assertions.hpp (used in three files) and one in tests/test_helpers.hpp (used everywhere else).

@niklas-uhl and I decided to just try to remove the lesser used version and see what happens even though we vaguely remembered what happened now: If the KASSERT fails only one some ranks, the test will fail.

The two redefinitions of KASSERT_KASSERT_HPP_KASSERT_IMPL take the following two approaches:

tests/test_assertions.hpp: Make KASSERT throw an exception on error. Will give a compilation warning (=error) for KASSERTs in destructors because they might throw during stack unwinding which will std::terminate().

tests/assertion_helpers.hpp: Use GoogleTest's death tests to check if the program failed with a specific error message. Breaks some assertions as described above.

We thus need to do some of the following:

• Rename one of the implementations.
• Provide a KASSERT_DESTRUCTOR which doesn't get overwritten or don't use KASSERT in destructors
• Find a solution which works in both cases

@DanielSeemaier originally implemented those two methods, so his input might be valueable.

[Hespian]

What was this doing? (seems like removing it makes tests fail?)

Also, this is not a bug ;)

[lukashuebner]

@Hespian I updated the comment in the first message to include more details.

[niklas-uhl]

while currently the death test version is used more often, after writing some more death tests, it became clear that the version which overrides KASSERT by throwing exceptions is a lot more flexible and makes it easier to test. I renamed the death test version, so that we do not have an ambiguous name. It is currently used nowhere, because using only the exception version all tests succeed.