Add more checks in unit tests

[spidru]

Summary:

• Added calls to tests that were defined but not yet referenced
• Added relevant checks in test when_fake_func_called_then_const_arguments_captured

Checklist:

• [x] Your code builds clean without any errors or warnings
• [x] You are not breaking consistency
• [x] You have added unit tests
• [x] All tests and other checks pass