What should we do to make QTestLib an outstanding test framework for testing the Qt Framework?

Feel free to add your wishes for QTestLib to this ticket. 

• It should be possible to have more than one test case in an executable.
  • Rationale: Facilitate TDD/BDD, reusing code across test cases without adding test support libraries.
• Test cases should be composable, so setup/teardown code can be specialized and reused, similar to googletest or catch2.
  • Rationale: Facilitate separation between setup code and actual test steps. Reduce code duplication, and easier to maintain tests.
• Mocking support
  • Improve test coverage, especially when facing error conditions