call for more ert tests

[Glenn Morris]

There are a lot of bugs in Emacs. [1]
To me, too many of these feel like breakage of things that used to work
before, because of implementation changes, or whatever.

One thing that could help reduce this is more unit tests.
If you haven't used it, ERT makes it pretty easy to write tests.
Of course, many aspects of Emacs's behaviour are not easy to test (GUI
stuff, etc.), but many are. See test/automated/ for examples. [2]

For example, package.el seems like something that should have a test
suite.

So if you fix a bug, please consider adding a unit test to make sure it
does not come back. Or if you rewrite a lisp package, consider adding
tests at the same time to check that obvious functionality still works.

I know writing tests is maybe not as interesting as writing shiny new
features, but I think it will save work in the long run.


[1] E.g. http://debbugs.gnu.org/rrd/emacs.html

[2] I think it is a bit embarrassing that the limited test suite that we
have has been broken for months, though. Bugs 13064, 13662.