def is_test_file_name(file_name):
    """
    Returns whether the given file name is the name of a test file.
    
    Parameters
    ----------
    file_name : `str`
        A file's name.
    
    Returns
    -------
    is_test_file_name : `bool`
    """
    if file_name == 'test.py':
        return True
    
    if file_name.startswith('test_') and file_name.endswith('.py'):
        return True
    
    if file_name.endswith('_tests.py'):
        return True
    
    return False