Incorrectly merging when PR is probably ready: mergeable_state: undefined

[hongaar]

The action merged some pull requests while checks where still failing and/or required reviews were missing. This is an example output:

INFO  Event name: status
INFO  Skipping PR update, required label missing: please-rebase
INFO  Merging PR #142 feat: validate content type
INFO  PR is probably ready: mergeable_state: undefined
INFO  PR successfully merged!
INFO  Removed labels: [ { id: 1936467964,
    node_id: 'MDU6TGFiZWwxOTM2NDY3OTY0',
    url:
     'https://api.github.com/repos/exivity/proximity/labels/automerge',
    name: 'automerge',
    color: 'ededed',
    default: false,
    description: null } ]

These are the checks for last commit on the merged branch (in this example, there was also a required review missing):

And here is the full workflow:

name: automerge

on:
  pull_request:
    types:
      - labeled
      - unlabeled
      - synchronize
      - opened
      - edited
      - ready_for_review
      - reopened
      - unlocked
  pull_request_review:
    types:
      - submitted
  check_suite:
    types:
      - completed
  status: {}

jobs:
  automerge:
    runs-on: ubuntu-latest
    steps:
      - name: automerge
        uses: pascalgn/automerge-action@v0.8.0
        env:
          GITHUB_TOKEN: "${{ secrets.GITHUB_PAT }}"
          MERGE_LABELS: "automerge"
          MERGE_REMOVE_LABELS: "automerge"
          MERGE_METHOD: "squash"
          MERGE_COMMIT_MESSAGE: "pull-request-description"
          MERGE_FORKS: "false"
          UPDATE_LABELS: "please-rebase"
          UPDATE_METHOD: "rebase"

[pascalgn]

This looks like a duplicate of #61. Could you check if the information in that issue might help you?

Generally speaking, I only see two possibilities for this behaviour:

1. This action just calls the GitHub API to merge, so it could be a problem in the API itself, causing PRs to be merged even though they should not. I find this highly unlikely, but if you suspect that this might be the cause, you need to contact GitHub support directly
2. A wrong configuration. See Auto-Merged PR even though PR was not reviewed and checks did not pass #61. Possibly, the user from the "GITHUB_PAT" token is an administrator and is excluded from certain rules

[hongaar]

@pascalgn thanks for your response. Decreasing the access level for the user who issued the PAT (our bot user) seems to have solved the issue, so your second point was indeed the reason we were seeing this.

To help others with this, would you accept a PR describing this behaviour in the Limitations section of the readme?

[pascalgn]

Yes, that should be fine!