The test suite includes a test that validates if the parser is capable of parsing the largest 64-bit number. The specification does not mention such ability as mandatory: it uses the term SHOULD and requires implementations to throw an appropriate error if the number cannot be represented losslessly.
I do this in my own implementation which is limited to the maximum integer a 64-bit float can safely represent, however this causes the valid/integer/long to fail. I think this test is not relevant; or should consider an explicit error as a pass (and only fail if the parser returns a number that is not the one expected due to a potential truncation)