def METHOD_NAME(covtest):
    covtest.makefile("""
        def func():
            pass
    """)
    covtest.run()
    expected = check_coverage.Message(
        check_coverage.MsgType.perfect_file,
        'module.py',
        'module.py has 100% coverage but is not in perfect_files!')
    assert covtest.check(perfect_files=[]) == [expected]