bug#51941: Detect duplication of ERT tests

["Mattias Engdegård" <mattiase@acm.org>]

24 nov. 2021 kl. 10.29 skrev Ihor Radchenko <yantar92@gmail.com>:

> 1. load-file test-oc
>   1.1. test-oc requires test-ox
> 2. load file test-ox triggers error:
>   Debugger entered--Lisp error: (error "Test ‘test-org-export/bind-keyword’ redefined")

Thank you, that was very clear.

Best practice is to run each ERT test file in a separate Emacs process. This ensures isolation between the tests, which can be quite important, but also permits them to be run in parallel. Easiest is to do this from a Makefile but you could of course do it from a controlling Emacs process if you prefer that.

Now if you for some reason want to stick with running them all in a single process, which I would advice against, then at least avoid the load-file if the file has already been loaded. Maybe use `require` with a file argument instead of load-file.

As a last resort you could insert something like (ert-delete-all-tests) between the test runs, but then you would no longer get the benefit of the global ERT test duplication check that is the one advantage of running them all in the same process.