How to use the monkeytype.cli.main function in MonkeyType

def test_apply_stub_init(store, db_file, stdout, stderr, collector):
    """Regression test for applying stubs to testmodule/__init__.py style module layout"""
    with trace_calls(collector):
        func_foo()

    store.add(collector.traces)

    with mock.patch.dict(os.environ, {DefaultConfig.DB_PATH_VAR: db_file.name}):
        ret = cli.main(['apply', Foo.__module__], stdout, stderr)

    assert ret == 0
    assert 'warning:' not in stdout.getvalue()

def test_quiet_failed_traces(store, db_file, stdout, stderr):
    traces = [
        CallTrace(func, {'a': int, 'b': str}, NoneType),
        CallTrace(func2, {'a': int, 'b': int}, NoneType),
    ]
    store.add(traces)
    with mock.patch("monkeytype.encoding.CallTraceRow.to_trace", side_effect=MonkeyTypeError("the-trace")):
        ret = cli.main(['stub', func.__module__], stdout, stderr)
    assert "2 traces failed to decode" in stderr.getvalue()
    assert ret == 0

def test_pathlike_parameter(store, db_file, capsys, stdout, stderr):
    with mock.patch.dict(os.environ, {DefaultConfig.DB_PATH_VAR: db_file.name}):
        with pytest.raises(SystemExit):
            cli.main(['stub', 'test/foo.py:bar'], stdout, stderr)
        out, err = capsys.readouterr()
        assert "test/foo.py does not look like a valid Python import path" in err

def test_verbose_failed_traces(store, db_file, stdout, stderr):
    traces = [
        CallTrace(func, {'a': int, 'b': str}, NoneType),
        CallTrace(func2, {'a': int, 'b': int}, NoneType),
    ]
    store.add(traces)
    with mock.patch("monkeytype.encoding.CallTraceRow.to_trace", side_effect=MonkeyTypeError("the-trace")):
        ret = cli.main(['-v', 'stub', func.__module__], stdout, stderr)
    assert "WARNING: Failed decoding trace: the-trace" in stderr.getvalue()
    assert ret == 0

def test_display_list_of_modules_no_modules(store, db_file, stdout, stderr):
    with mock.patch.dict(os.environ, {DefaultConfig.DB_PATH_VAR: db_file.name}):
        ret = cli.main(['list-modules'], stdout, stderr)
    expected = ""
    assert stderr.getvalue() == expected
    expected = "\n"
    assert stdout.getvalue() == expected
    assert ret == 0

def test_cli_context_manager_activated(capsys, stdout, stderr):
    ret = cli.main(['-c', f'{__name__}:LoudContextConfig()', 'stub', 'some.module'], stdout, stderr)
    out, err = capsys.readouterr()
    assert out == "IN SETUP: stub\nIN TEARDOWN: stub\n"
    assert err == ""
    assert ret == 0

def test_no_traces(store, db_file, stdout, stderr, arg, error):
    with mock.patch.dict(os.environ, {DefaultConfig.DB_PATH_VAR: db_file.name}):
        ret = cli.main(['stub', arg], stdout, stderr)
    assert stderr.getvalue() == error
    assert stdout.getvalue() == ''
    assert ret == 0

def test_generate_stub(store, db_file, stdout, stderr):
    traces = [
        CallTrace(func, {'a': int, 'b': str}, NoneType),
        CallTrace(func2, {'a': int, 'b': int}, NoneType),
    ]
    store.add(traces)
    ret = cli.main(['stub', func.__module__], stdout, stderr)
    expected = """def func(a: int, b: str) -> None: ...


def func2(a: int, b: int) -> None: ...
"""
    assert stdout.getvalue() == expected
    assert stderr.getvalue() == ''
    assert ret == 0

def test_display_sample_count_from_cli(store, db_file, stdout, stderr):
    traces = [
        CallTrace(func, {'a': int, 'b': str}, NoneType),
        CallTrace(func2, {'a': int, 'b': int}, NoneType),
    ]
    store.add(traces)
    with mock.patch.dict(os.environ, {DefaultConfig.DB_PATH_VAR: db_file.name}):
        ret = cli.main(['stub', func.__module__, '--sample-count'], stdout, stderr)
    expected = """Annotation for tests.test_cli.func based on 1 call trace(s).
Annotation for tests.test_cli.func2 based on 1 call trace(s).
"""
    assert stderr.getvalue() == expected
    assert ret == 0

def test_toplevel_filename_parameter(store, db_file, stdout, stderr):
    filename = 'foo.py'
    with mock.patch.dict(os.environ, {DefaultConfig.DB_PATH_VAR: db_file.name}):
        orig_exists = os.path.exists

        def side_effect(x):
            return True if x == filename else orig_exists(x)
        with mock.patch('os.path.exists', side_effect=side_effect) as mock_exists:
            ret = cli.main(['stub', filename], stdout, stderr)
            mock_exists.assert_called_with(filename)
        err_msg = f"No traces found for {filename}; did you pass a filename instead of a module name? " \
                  f"Maybe try just '{os.path.splitext(filename)[0]}'.\n"
        assert stderr.getvalue() == err_msg
        assert stdout.getvalue() == ''
        assert ret == 0