[rmetzler]

For linux, there is faketime, which will set a specific date and time for all child processes. This enables you to test software you don't even compile for time-based problems, e.g. logic around Feb 29th or daylight saving time.

[TheDong]

Since go don’t use the libc related time functions on linux, but rather makes syscalls directly, faketime will not work for any programs written in Go.

[rmetzler]

Thank you for clarifying.

[zokier]

LD_PRELOAD is bit yucky though in my opinion. I suppose ptrace is the only other option though :/

[deivid]

It's not the only other option! It's not less yucky, but you can creatively stomp on the vDSO functions which back the time-related functions (gettimeofday, clock_gettime, time); I've written about it at [0] and have a "library" (more like a proof of concept) at [1].

[0]: https://blog.davidv.dev/posts/cursing-a-process-vdso-for-tim...

[1]: https://github.com/DavidVentura/tpom