Refactor unit tests to use more convenient doctest assertion macros

[kkarbowiak]

Hello,

Since version 2.3.5 doctest supports new assertion macros that assert both exception type and message, in the form of *_THROWS_WITH_AS (e.g. CHECK_THROWS_WITH_AS).

With those, some code duplication in unit tests can be avoided, as for example the following (test/src/unit-constructor1.cpp):

CHECK_THROWS_AS((j.get<std::pair<int, int>>()), json::out_of_range&);
CHECK_THROWS_WITH((j.get<std::pair<int, int>>()), "[json.exception.out_of_range.401] array index 1 is out of range");

can be replaced with:

CHECK_THROWS_WITH_AS((j.get<std::pair<int, int>>()), "[json.exception.out_of_range.401] array index 1 is out of range", json::out_of_range&);

Would you be interested in that? If so, I can create a pull request.

[nlohmann]

Hey @kkarbowiak - yes, why not! I hope you can do this automatically as there are 979 CHECK_THROWS_AS calls and 1020 CHECK_THROWS_WITH calls...

[kkarbowiak]

I hope so too ;-) I will get back with a PR.