Support closure in REGISTER_TEST_CASE macros.

[willir]

REGISTER_TEST_CASE accepts only raw pointer to free function,
Sometimes it is convenient to generate several test_cases based on same
function but with different data.

For example: if one has bunch of inputs for which tested library should
produce certain outputs. In other word if one wants to write something
like:

for(const auto &testData : testDataList) {
    REGISTER_TEST_CASE(std::bind(&testCase, testData), "test_case_" + testData.name);
}

In this case raw pointers doesn't work. So REGISTER_TEST_CASE should
support std::function.

This support should be enabled only if compiler supports C++11.
For that purpose CATCH_CONFIG_CPP11_STD_FUNCTION define should be added.

Also it is required to change type of members of class Catch::NameAndDesc from raw char pointer to std::string, to allow one register test cases with different names in the loop easily.

[philsquared]

Interesting.
I'm not against this, but I have a few observations (and would need to think about it a bit more):

1. wrt, "if one has bunch of inputs for which tested library should produce certain outputs" - that sounds a lot like a property-based testing approach. I have a first class implementation of this in the works. That said I've been promising it for a while and its not ready yet (it's a big chunk of work and my time is limited).
2. IIRC I originally made Catch::NameAndDesc raw char*s because I found that using std::string in those self-registering constructor seemed to add a lot of compile time overhead - at least in XCode. That was some years ago (and Catch itself was smaller and simpler). I should probably revisit that to see if there is still an issue.

Thanks for proposing this. I'll try and get back to you on it.