feat: Handle Merge Queues

README.md

@@ -215,6 +215,46 @@ jobs:
           GITHUB_TOKEN: ${{ github.token }}
 ```
 
+### Using with merge queues
+
+If you are using merge queues, you will need to add the `merge_group` event to your workflow's `on:` clause. This will ensure that the action is triggered when a pull request is added to the merge queue.
+
+You will need to ensure the action is run only _after_ all the actual merge checks have run. Otherwise, coverage data will be incorrectly updated.
+
+For instance
+
+```yaml
+# .github/workflows/ci.yml
+name: CI
+
+on:
+  pull_request:
+  merge_group:
+
+jobs:
+  test:
+    name: Run tests & display coverage
+    runs-on: ubuntu-latest
+    permissions:
+      # Gives the action the necessary permissions for publishing new
+      # comments in pull requests.
+      pull-requests: write
+      # Gives the action the necessary permissions for pushing data to the
+      # python-coverage-comment-action branch, and for editing existing
+      # comments (to avoid publishing multiple comments in the same PR)
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install everything, run the tests, produce the .coverage file
+        run: make test # This is the part where you put your own test command
+
+      - name: Coverage comment
+        uses: py-cov-action/python-coverage-comment-action@v3
+        with:
+          GITHUB_TOKEN: ${{ github.token }}
+```
+
 ### Merging multiple coverage reports
 
 In case you have a job matrix and you want the report to be on the global

coverage_comment/activity.py

@@ -27,12 +27,13 @@ def find_activity(
         (event_name == "push" and is_default_branch)
         or event_name == "schedule"
         or (event_name == "pull_request" and event_type == "closed")
+        or event_name == "merge_group"
     ):
         if event_name == "pull_request" and event_type == "closed" and not is_pr_merged:
             raise ActivityNotFound
         return "save_coverage_data_files"
 
-    if event_name not in {"pull_request", "push"}:
+    if event_name not in {"pull_request", "push", "merge_group"}:
         raise ActivityNotFound
 
     return "process_pr"

coverage_comment/main.py

@@ -83,7 +83,7 @@ def action(
     except activity_module.ActivityNotFound:
         log.error(
             'This action has only been designed to work for "pull_request", "push", '
-            f'"workflow_run" or "schedule" actions, not "{event_name}". Because there '
+            f'"workflow_run", "schedule" or "merge_group" actions, not "{event_name}". Because there '
             "are security implications. If you have a different usecase, please open an issue, "
             "we'll be glad to add compatibility."
         )

tests/unit/test_activity.py

@@ -15,6 +15,7 @@
         ("pull_request", True, None, False, "process_pr"),
         ("pull_request", False, None, False, "process_pr"),
         ("schedule", False, None, False, "save_coverage_data_files"),
+        ("merge_group", False, None, False, "save_coverage_data_files"),
     ],
 )
 def test_find_activity(