Add test for IsUserAllowedToMerge with action user

[lunny]

Add a test for #31056

[delvh]

Suggested change

	func Test_IsUserAllowedToMerge(t *testing.T) {
	func Test_ActionsUserCannotMerge(t *testing.T) {

[yp05327]

The root reason is here.
We only check the permission, and ignore the doer when white list is disabled.
Action user has the permission, but should not be allowed to merge.
So if you change the permission in test, it will fail.

[yp05327]

the test is not correct

[yp05327]

more details:

if you print the permission and the user, you can see action user has the permission, so IsUserMergeWhitelisted will return true.

the workflow

name: test
on : push

jobs:  
  test:
    runs-on: ubuntu-latest
    steps:
      - name: Test
        run: |
          jq -n '{
              "Do": "merge",
              "MergeCommitID": "xxxxxxxx",
              "MergeMessageField": "MergeMessageField",
              "MergeTitleField": "MergeTitleField",
              "delete_branch_after_merge": true,
              "force_merge": false,
              "head_commit_id": "xxxxxxxx",
              "merge_when_checks_succeed": true
          }' | curl "http://172.17.0.2:3000/api/v1/repos/testorg/testaction/pulls/5/merge" -H "accept: application/json" -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" -H "Content-Type: application/json" -d @-

[yp05327]

the write permission comes from here:

[lunny]

Replaced by #31173