A quick note on testing custom GitHub Actions

Posted on November 20, 2022

I was working on a (very simple) GitHub Action this one and was uncertain how to test it. It turns out the obvious solution works: create a workflow file as usual in the action repository itself which then has a step where it uses itself by name and specifies HEAD as the revision. Example:

steps:
  - id: test
    uses: diku-dk/install-futhark@HEAD

It’s sort of obvious why it works, which I always like, but I couldn’t find this trick documented anywhere. The tutorial suggests creating a release of the action and testing it from another repository, which is of course horrible unergonomic. I don’t know if the above can be improved (it doesn’t handle branches for example), but it was good enough for simple things.