def testNotANumber(self, message_module):
    golden_data = (b'\x5D\x00\x00\xC0\x7F'
                   b'\x61\x00\x00\x00\x00\x00\x00\xF8\x7F'
                   b'\xCD\x02\x00\x00\xC0\x7F'
                   b'\xD1\x02\x00\x00\x00\x00\x00\x00\xF8\x7F')
    golden_message = message_module.TestAllTypes()
    golden_message.ParseFromString(golden_data)
    self.assertTrue(isnan(golden_message.optional_float))
    self.assertTrue(isnan(golden_message.optional_double))
    self.assertTrue(isnan(golden_message.repeated_float[0]))
    self.assertTrue(isnan(golden_message.repeated_double[0]))

    # The protocol buffer may serialize to any one of multiple different
    # representations of a NaN.  Rather than verify a specific representation,
    # verify the serialized string can be converted into a correctly
    # behaving protocol buffer.
    serialized = golden_message.SerializeToString()
    message = message_module.TestAllTypes()
    message.ParseFromString(serialized)
    self.assertTrue(isnan(message.optional_float))
    self.assertTrue(isnan(message.optional_double))
    self.assertTrue(isnan(message.repeated_float[0]))
    self.assertTrue(isnan(message.repeated_double[0]))