def make_main_etc(self) -> None:
        """Make main.py and m1-m3.py for other tests."""
        self.make_file("main.py", """\
            import m1
            import m2
            import m3

            a = 5
            b = 6

            assert m1.m1a == 1
            assert m2.m2a == 1
            assert m3.m3a == 1
            """)
        self.make_file("m1.py", """\
            m1a = 1
            m1b = 2
            """)
        self.make_file("m2.py", """\
            m2a = 1
            m2b = 2
            """)
        self.make_file("m3.py", """\
            m3a = 1
            m3b = 2
            """)
Make main.py and m1-m3.py for other tests.
tests/test_html.py