There is a python that says "unittest"?@classmethod?

test_graph.py is a unit test module, but python test_graph.py does nothing because there is no code to execute.Now start the test from the command line.For example, you can test with the following commands:

 python-unit test tests/test_graph.py

·Reference Official Document unittest 26.4.2. Command Line Interface

Also, @classmethod is used, but I don't think this question is very important, so setUpClass() is the method called before the test runs, and tearDownClass() is the method called after the test runs.