'Return list of tuples zipped from uri_str cases and
*expected_values*. Raise if lengths don\'t match.'

def cases(self, expected_values):

    uri_str_cases = ['/', '/ppt/presentation.xml', '/ppt/slides/slide1.xml']
    if (len(expected_values) != len(uri_str_cases)):
        msg = 'len(expected_values)    differs    from    len(uri_str_cases)'
        raise AssertionError(msg)
    pack_uris = [PackURI(uri_str) for uri_str in uri_str_cases]
    return zip(pack_uris, expected_values)
