GitHub Actions SHA doesn't always work for pull requests

[aslakhellesoy]

👓 What did you see?

No after property in /home/runner/work/_temp/_github_workflow/event.json:

Followed by the contents of the file:

{
  "action": "opened",
  "pull_request": {
    "base": {
      "sha": "1c668f7546a31cfa77f486970af0d642634b6db0"
    },
    "head": {
      "sha": "d79b417f8e974b9a2d5e6483845a96446695f944"
    }
  }
}

(I have only included relevant properties in the JSON)

✅ What did you expect to see?

I had expected to see no error, and an event payload like this:

{
  "action": "synchronize",
  "after": "3738117e3337e54955580f4e98cf767d96b42135",
  "before": "06aa815724888e86f37e41e43e07b0ec1bb0ffe1"
}

(I have only included relevant properties in the JSON)

Upon further inspection, it seems both the synchronize event and open events include a .pull_request.head.sha property that can be used in both cases.

This makes the Java implementation a bit more complicated since it relies on regexp matching rather than using a JSON parser. We can probably fix this by skipping pas the head property before we grab the sha.

[aslakhellesoy]

From what I can tell, the event is opened when a PR is first created. If new commits are pushed to the same PR, the events are synchronize.