There was a problem with the Vagrant tests where the year 2016 was hard-coded in as the modified date. This had to be done to make the --long tests use the correct date format, which varies depending on whether the timestamp is in the current year.
Unfortunately, time progresses [citation needed], and what was once 2016 is now 2017, so the date format changed and the tests broke.
Because the Vagrantfile is just a Ruby script, we can look up the current year at runtime and use that instead. There’s also a check added to the test runner that makes sure none of the files are more than 365 days old, because if any are, then it’s time to update the timestamps (or it’s the last day of a leap year)
See the README section for more details. Basically, with this way, we can store a bunch of existing valid exa outputs, change a VM's environment to match our values, then check that exa still works by comparing outputs.
