Similar to the change that removed `std::set` from the test registration path, this saves an allocation per test to run, and is faster to boot. Technically, the performance of selecting tests for multiple OR-joined filters, each of which selects many (most) tests is a bit slower, but that is not very common use case.
This is _technically_ a performance improvement, but in actuality it is a tiny cleanup so it stops bothering me.
We used to store a full vector of "views" of the registered test infos, so that it can be retrieved externally. However, the only user of that interface left was `Session`, specifically `Session::applyFilenameAsTags`. By moving the adding of the filename tags into the `ITestCaseRegistry` interface, we avoid storing the vector and make the initial test registration faster. The new code is ugly and shows a design/layering issue, but no worse than the previous approach did.
The old internals reached into the global hub to stash the allocation(s) for enum value -> string value there, then kept around a potentially invalid (in case the hub was cleaned up) reference into it, going through whole bunch of virtual dispatch in the process. The new internals just store the data in a static variable inside the `StringMaker` specialization. This avoids potential lifetime issues, avoids all virtual dispatch and (almost) reduces the include bloat in the main header path. The reason for (almost) there is that for full include correctness, `EnumInfo` needs `<utility>` include for `std::pair`. However, this brings in things like `std::relops`, because the std headers in C++ are dumb. As this was not included before, and instead we relied on `std::pair` existing in an internal stdlib header that we transitively included, the full include size ends up bigger than before.
This tells Catch2 to create an empty file at specified path before the tests start, and delete it after the tests finish. This allows callers to catch cases where the test binary silently exits before finishing (e.g. via call to `exit(0)` inside the code under test), by looking whether the file still exists. Closes #3020
The main reason for this is to be able to distinguish between different errors (or "errors") based on the return code. Before this change, it was impossible to use the exit code to figure out whether a test binary failed because all tests were skipped or because exactly 4 assertions have failed. This meant that using `catch_discover_tests` and telling it to check for exit code == 4 to determine skipped tests could lead to false negatives.