def METHOD_NAME():
    """
    Test if it cleans the cached NPM packages.
    """
    mock = MagicMock(return_value={"retcode": 1, "stderr": "error"})
    with patch.dict(npm.__salt__, {"cmd.run_all": mock}):
        assert not npm.cache_clean()
    mock = MagicMock(return_value={"retcode": 0})
    with patch.dict(npm.__salt__, {"cmd.run_all": mock}):
        assert npm.cache_clean()
    mock = MagicMock(return_value={"retcode": 0})
    with patch.dict(npm.__salt__, {"cmd.run_all": mock}):
        assert npm.cache_clean("coffee-script")