def create_initial_files(self) -> None:
        """
        Helper for tests that handles the common ceremony so the tests can
        show the consequences of changes in the setup.
        """
        self.make_file("main_file.py", """\
            def cuboid_volume(l):
                return (l*l*l)

            def IsItTrue():
                return True
            """)

        self.make_file("test_file.py", """\
            from main_file import cuboid_volume
            import unittest

            class TestCuboid(unittest.TestCase):
                def test_volume(self):
                    self.assertAlmostEqual(cuboid_volume(2),8)
                    self.assertAlmostEqual(cuboid_volume(1),1)
                    self.assertAlmostEqual(cuboid_volume(0),0)
                    self.assertAlmostEqual(cuboid_volume(5.5),166.375)
            """)

        Helper for tests that handles the common ceremony so the tests can
        show the consequences of changes in the setup.
        
tests/test_lcov.py