At my day job, there is only tests for approximately 20% of all code. They've finally mandated that all files get at least 80% coverage (this is all Python). I'm a stickler in my Perl apps to reach at least 90% coverage, but frequently reach 95+, testing most things in numerous way at that.

I'm also currently half way done a tutorial for PerlMonks that shows the whole github, travis and coveralls configuration so those who don't know, will easily be able to implement and appreciate CI