google/googletest ? reverse-engineered prompt

Build me a comprehensive testing and mocking framework for C++. The idea is to create a professional-grade, xUnit-style library to help developers write unit tests for their C++ code. It shouldn't require developers to manually register their tests; instead, it should automatically discover and run them.

Please include a rich set of assertions for checking things like equality, exceptions, and other common conditions. It's also important that developers can create their own custom assertions. I need a feature for "death tests" to verify that the code crashes or exits when it's supposed to. Also, some test failures should be fatal, while others should be non-fatal and allow other tests to continue. To make testing more efficient, let's support running the same test with different input values or even different data types. It should be built for modern C++.