Describe an exception type instance with a human readable string representation

Used in: Global scope, preferably in the translation unit containing the main() function

Requirement: signature is a function parameter list with one parameter being the type of the exception to describe

Requirement: A code block follows immediately after.

The code block returns a std::string that describes, in a human readable form, the exception object in the parameter list.

The macro CRPCUT_DESCRIBE_EXCEPTION(signature) may be invoked any number of times, even using the same signature. When an unexpected exception is encountered, the describers will be tried, one by one, in the order they are defined, until one matches.

	Note
	The order that exception describers from different translation units are tried is undefined. It is thus a bad idea to add them in more than one file.

Example: The test program

     
     #include <crpcut.hpp>
     #include <vector>
     #include <limits>
     
     CRPCUT_DESCRIBE_EXCEPTION(std::out_of_range &r)
     {
       return std::string("a reference to an out_of_range(\"") + r.what() + "\") object";
     }
     
     TEST(make_mighty_big)
     {
       std::vector<int> v;
       v.reserve(std::numeric_limits<size_t>::max());
     }
     
     TEST(access_past_end)
     {
       std::vector<int> v;
       v.at(3);
     }
     
     int main(int argc, char *argv[])
     {
       return crpcut::run(argc, argv);
     }

      

reports two failed tests:

     FAILED!: make_mighty_big
     phase="running"  --------------------------------------------------------------
     samples/describe_exception.cpp:37
     Unexpectedly caught std::exception
     	what()=vector::reserve
     -------------------------------------------------------------------------------
     ===============================================================================
     FAILED!: access_past_end
     phase="running"  --------------------------------------------------------------
     samples/describe_exception.cpp:43
     Unexpectedly caught a reference to an out_of_range("vector::_M_range_check: __n (which is 3) >= this->size() (which is 0)") object
     -------------------------------------------------------------------------------
     ===============================================================================
     2 test cases selected
     
                    Sum   Critical   Non-critical
     FAILED   :       2          2              0

      

The first exception type does not have a custom describer, but since it inherits from std::exception, some information is shown anyway. The second exception matches the signature used for the custom describer, and thus the message looks as expected.