Check stepUp() and stepDown() bahevior for type=time. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Invalid value PASS stepUp("", null, null) is "00:01" PASS stepDown("", null, null) is "00:00" Non-number arguments PASS stepUp("20:13", null, null, "0") is "20:13" PASS stepDown("20:13", null, null, "0") is "20:13" PASS stepUp("20:13", null, null, "foo") is "20:13" PASS stepDown("20:13", null, null, "foo") is "20:13" PASS stepUp("20:13", null, null, null) is "20:13" PASS stepDown("20:13", null, null, null) is "20:13" Normal cases PASS stepUp("20:13", null, null) is "20:14" PASS stepDown("20:13", null, null) is "20:12" PASS stepUp("20:13", null, null, 10) is "20:23" PASS stepDown("20:13", null, null, 11) is "20:02" PASS stepUp("20:13", "4", null, 2) is "20:13:08" PASS stepDown("20:13", "4", null, 3) is "20:12:48" Step=any PASS stepUp("20:13", "any", null) threw exception InvalidStateError: The object is in an invalid state.. PASS stepDown("20:13", "any", null) threw exception InvalidStateError: The object is in an invalid state.. Overflow/underflow PASS stepUp("20:13", "3.40282346e+38", null) is "20:13" PASS stepDown("20:13", "3.40282346e+38", null) is "00:00:00" PASS stepUp("20:13", "1", "20:13") is "20:13:00" PASS stepDown("20:13", "1", "20:13") is "20:13:00" PASS stepUp("23:59", null, null) is "23:59" PASS stepDown("00:00", null, null) is "00:00" PASS successfullyParsed is true TEST COMPLETE