def METHOD_NAME(testcase: DataDrivenTestCase, step: int) -> None:
    assert testcase.old_cwd is not None, "test was not properly set up"
    # Write the program to a file.
    program = "_program.py"
    program_path = os.path.join(test_temp_dir, program)
    with open(program_path, "w", encoding="utf8") as file:
        for s in testcase.input:
            file.write(f"{s}\n")
    args = parse_args(testcase.input[0])
    custom_cwd = parse_cwd(testcase.input[1]) if len(testcase.input) > 1 else None
    args.append("--show-traceback")
    if "--error-summary" not in args:
        args.append("--no-error-summary")
    if "--show-error-codes" not in args:
        args.append("--hide-error-codes")
    if "--disallow-empty-bodies" not in args:
        args.append("--allow-empty-bodies")
    if "--no-force-uppercase-builtins" not in args:
        args.append("--force-uppercase-builtins")
    if "--no-force-union-syntax" not in args:
        args.append("--force-union-syntax")
    # Type check the program.
    fixed = [python3_path, "-m", "mypy"]
    env = os.environ.copy()
    env.pop("COLUMNS", None)
    extra_path = os.path.join(os.path.abspath(test_temp_dir), "pypath")
    env["PYTHONPATH"] = PREFIX
    if os.path.isdir(extra_path):
        env["PYTHONPATH"] += os.pathsep + extra_path
    cwd = os.path.join(test_temp_dir, custom_cwd or "")
    args = [arg.replace("$CWD", os.path.abspath(cwd)) for arg in args]
    process = subprocess.Popen(
        fixed + args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, cwd=cwd, env=env
    )
    outb, errb = process.communicate()
    result = process.returncode
    # Split output into lines.
    out = [s.rstrip("\n\r") for s in str(outb, "utf8").splitlines()]
    err = [s.rstrip("\n\r") for s in str(errb, "utf8").splitlines()]
    if "PYCHARM_HOSTED" in os.environ:
        for pos, line in enumerate(err):
            if line.startswith("pydev debugger: "):
                # Delete the attaching debugger message itself, plus the extra newline added.
                del err[pos : pos + 2]
                break
    # Remove temp file.
    os.remove(program_path)
    # Compare actual output to expected.
    if testcase.output_files:
        # Ignore stdout, but we insist on empty stderr and zero status.
        if err or result:
            raise AssertionError(
                "Expected zero status and empty stderr%s, got %d and\n%s"
                % (" on step %d" % step if testcase.output2 else "", result, "\n".join(err + out))
            )
        check_test_output_files(testcase, step)
    else:
        if testcase.normalize_output:
            out = normalize_error_messages(err + out)
        obvious_result = 1 if out else 0
        if obvious_result != result:
            out.append(f"== Return code: {result}")
        expected_out = testcase.output if step == 1 else testcase.output2[step]
        # Strip "tmp/" out of the test so that # E: works...
        expected_out = [s.replace("tmp" + os.sep, "") for s in expected_out]
        assert_string_arrays_equal(
            expected_out,
            out,
            "Invalid output ({}, line {}){}".format(
                testcase.file, testcase.line, " on step %d" % step if testcase.output2 else ""
            ),
        )