Specifying tests / selecting tests
Several test run options:

• pytest test_mod.py # run tests in module
• pytest somepath # run all tests below somepath
• pytest -k stringexpr # only run tests with names that match the "string expression", e.g. "MyClass and not method" will select TestMyClass.test_something but not TestMyClass.test_method_simple
• pytest test_mod.py::test_func # only run tests that match the "node ID", e.g. "test_mod.py::test_func" will select only test_func in test_mod.py
• pytest test_mod.py::TestClass::test_method # run a single method in a single class