I had a unit tests for a Java LocalDate that was being increased by one year. It checked whether the month and day were the same, and failed because the current day (29) didn't equal the year-hence one (28). I changed it to check that the difference between the days was less than two.
Ask HN: Did you encounter any leap year bugs today?
131–140 of 498 posts
Re: Ask HN: Did you encounter any leap year bugs today?
#132Why are there so many stories about leap year bugs?
Because programmers take shortcuts. Its easier to type x - 365 than to import Calendar and then date(x) - timedelta(1 year).
And standard library design errors also.
Properly designed date/time API invented relatively recently.
System.DateTime (.NET) - 2002 | System.DateTimeOffset - 2005
Joda time (JVM) - 2005 | java.time - 2014
Temporal (JavaScript) - still experimental
Re: Ask HN: Did you encounter any leap year bugs today?
#133I can understand getting the years 2000 (leap), 2100 (not leap), 2200 (not leap), and 2300 (not leap) wrong. But getting the year 2024 wrong is, disappointing, to put it diplomatically.
Those are harder to get wrong, since leap year bugs are almost always from consumers of dates. To screw up a not-a-leap-year-year you'd need to produce a bogus February 29 on a real March 1. Date producers tend to understand how the calendar works better than that.
Re: Ask HN: Did you encounter any leap year bugs today?
#134The other way around! Today a few services that don't congratulate me on my birthday (on non-leap years) did. I was born on February 29th.
...it occurs to me, when should those services congratulate you? Should it be on February 28 or March 1?
Re: Ask HN: Did you encounter any leap year bugs today?
#135> and SRE has scheduled a postmortem after the QA confirms the fix in 2028.
:)
Re: Ask HN: Did you encounter any leap year bugs today?
#136Heard from a friend in China: the age calculation portion of the app to schedule a marriage certificate had a bug where they subtracted 22 (legal minimum age) from the year, which resulted in 2002-02-29 which doesn't exist. The app intends to compare this against the user's birth date. The error handling code assumes all errors are from the comparison. The app then rejected all marriage certificate appointments by co…
Haha, that would be quite the appropriate place to put one of those "Please wait and try again" error messages.
"look, today the math just doesn't work out, try tomorrow"
Re: Ask HN: Did you encounter any leap year bugs today?
#137I had a unit tests for a Java LocalDate that was being increased by one year. It checked whether the month and day were the same, and failed because the current day (29) didn't equal the year-hence one (28). I changed it to check that the difference between the days was less than two.
Previously your unit test was broken one day every four ish years. Now it's broken every day :)
Re: Ask HN: Did you encounter any leap year bugs today?
#138I had to renew my vehicle registration this month. You usually have until the last day of the month to get it done. But this year the state of North Carolina said that was the 28th, not the 29th.
Re: Ask HN: Did you encounter any leap year bugs today?
#139The other way around! Today a few services that don't congratulate me on my birthday (on non-leap years) did. I was born on February 29th.
...it occurs to me, when should those services congratulate you? Should it be on February 28 or March 1?
According to the government, Mar 1. Anything that is based on your birthday (driver's license, drinking, signing contracts, etc) all happen on March 1 if there is no Feb 29 that year.
Which makes sense since then it is "after" your birthday.
Re: Ask HN: Did you encounter any leap year bugs today?
#140Pretty much all of the self service gas station terminals in New Zealand went down for the 29th