Testing Code That is Difficult to Test (With Perl)
Code that performs side effects is difficult to test because we need figure out how to sandbox the effects so we can observe the state of the sandbox before and after executing the effectful code. The difficulty is increased when the side effectful code also depends on specific OS configurations. Let us explore my solution to such a predicament.
Source: Testing Code That is Difficult to Test (With Perl), an article by Nicholas Hubbard.