I write tests for every single module I create. That includes personal and $work modules. And the first one is always 00-load.t.

Writing tests is extremely important — I can't stress this strongly enough.

Run 'make test' every time you change Module.pm; that provides a regression test. Now write one or more new tests that address whatever changes you made. If you're only changing a test, or want more specific feedback from a test, use 'prove -vb t/whatever.t'.

It might seem like extra work but, in the long run, it will save you much time and frustration. If you use something like Module::Starter, some tests will be automatically written for you; you can write generic test templates which you copy to 't/' and then just do a global substitution, e.g. s/___MODULE_NAME___/Module::Name/g; you can write boilerplate tests which you can just copy and leave as is (see 't/99-02_manifest.t' in "Re: Perl tools for making code better" for an example — that's the first block of code; the filename is mentioned further down).

I absolutely concur with ++stevieb's "famous last words" comment.