Tests error messages to make sure that they're sane

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".


PASS parseTest('0x') is "No hexadecimal digits after '0x'"
PASS parseTest('0xg') is "No hexadecimal digits after '0x'"
PASS parseTest('0x1.2') is "Unexpected number '.2'. Parse error."
PASS parseTest('0x1g') is "No space between hexadecimal literal and identifier"
PASS parseTest('0x1in') is "No space between hexadecimal literal and identifier"
PASS successfullyParsed is true

TEST COMPLETE