Add test

Author: Mariatta

tests/test_tasks.py

@@ -0,0 +1,60 @@
+import os
+import subprocess
+from unittest import mock
+
+from cherry_picker import cherry_picker
+
+os.environ.setdefault("HEROKU_REDIS_MAROON_URL", "someurl")
+
+from miss_islington import tasks
+
+
+async def test_invalid_repo_exception_posts_comment_and_clears_state():
+    """A stuck cherry-picker.state in git config used to wedge every
+    subsequent backport: CherryPicker() init raised InvalidRepoException
+    and the task crashed with no comment posted. The task now wipes
+    stale state pre-flight and posts an error comment if init still fails.
+    """
+    with (
+        mock.patch("miss_islington.tasks.aiohttp.ClientSession"),
+        mock.patch(
+            "miss_islington.tasks.apps.get_installation_access_token",
+            new=mock.AsyncMock(return_value={"token": "test-token"}),
+        ),
+        mock.patch("miss_islington.tasks.util.is_cpython_repo", return_value=True),
+        mock.patch("miss_islington.tasks.subprocess.check_output"),
+        mock.patch("miss_islington.tasks.subprocess.run") as run_mock,
+        mock.patch(
+            "miss_islington.tasks.cherry_picker.CherryPicker",
+            side_effect=cherry_picker.InvalidRepoException("stuck state"),
+        ),
+        mock.patch(
+            "miss_islington.tasks.util.comment_on_pr", new=mock.AsyncMock()
+        ) as comment_mock,
+        mock.patch(
+            "miss_islington.tasks.util.assign_pr_to_core_dev", new=mock.AsyncMock()
+        ) as assign_mock,
+    ):
+        await tasks.backport_task_asyncio(
+            "7a4c6dfb8839eb05fb87baf70364680e45001dd4",
+            "3.15",
+            issue_number=130749,
+            created_by="medmunds",
+            merged_by="bitdancer",
+            installation_id=42958231,
+        )
+
+    run_mock.assert_any_call(
+        ["git", "config", "--local", "--remove-section", "cherry-picker"],
+        stderr=subprocess.DEVNULL,
+        check=False,
+    )
+
+    comment_mock.assert_awaited_once()
+    posted_message = comment_mock.await_args.args[2]
+    assert "3.15" in posted_message
+    assert "@bitdancer" in posted_message
+
+    assign_mock.assert_awaited_once()
+    assert assign_mock.await_args.args[1] == 130749
+    assert assign_mock.await_args.args[2] == "bitdancer"