phabricator/tasks: Fix task function return type

Previously, the following error was raised when the task has finished
its execution: "Object of type ListerStats is not JSON serializable".

So ensure ListerStats object gets converted to dict before returning it.

Also add missing test for task function.

swh/lister/phabricator/tasks.py

@@ -2,7 +2,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from typing import Optional
+from typing import Dict, Optional
 
 from celery import shared_task
 
@@ -10,11 +10,17 @@ from swh.lister.phabricator.lister import PhabricatorLister
 
 
 @shared_task(name=__name__ + ".FullPhabricatorLister")
-def list_phabricator_full(url: str, instance: str, api_token: Optional[str] = None):
+def list_phabricator_full(
+    url: str, instance: str, api_token: Optional[str] = None
+) -> Dict[str, int]:
     """Full update of a Phabricator instance"""
-    return PhabricatorLister.from_configfile(
-        url=url, instance=instance, api_token=api_token
-    ).run()
+    return (
+        PhabricatorLister.from_configfile(
+            url=url, instance=instance, api_token=api_token
+        )
+        .run()
+        .dict()
+    )
 
 
 @shared_task(name=__name__ + ".ping")

swh/lister/phabricator/tests/test_tasks.py

@@ -1,7 +1,11 @@
-# Copyright (C) 2019-2020 the Software Heritage developers
+# Copyright (C) 2019-2021 the Software Heritage developers
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from unittest.mock import patch
+
+from swh.lister.pattern import ListerStats
+
 
 def test_ping(swh_scheduler_celery_app, swh_scheduler_celery_worker):
     res = swh_scheduler_celery_app.send_task("swh.lister.phabricator.tasks.ping")
@@ -9,3 +13,29 @@ def test_ping(swh_scheduler_celery_app, swh_scheduler_celery_worker):
     res.wait()
     assert res.successful()
     assert res.result == "OK"
+
+
+@patch("swh.lister.phabricator.tasks.PhabricatorLister")
+def test_phabricator_lister_task(
+    lister, swh_scheduler_celery_app, swh_scheduler_celery_worker
+):
+    # setup the mocked PhabricatorLister
+    lister.from_configfile.return_value = lister
+    lister_stats = ListerStats(pages=2, origins=200)
+    lister.run.return_value = lister_stats
+
+    task_params = {
+        "url": "https://forge.softwareheritage.org/api/diffusion.repository.search",
+        "instance": "swh",
+        "api_token": None,
+    }
+
+    res = swh_scheduler_celery_app.send_task(
+        "swh.lister.phabricator.tasks.FullPhabricatorLister", kwargs=task_params
+    )
+    assert res
+    res.wait()
+    assert res.successful()
+    assert res.result == lister_stats.dict()
+
+    lister.from_configfile.assert_called_once_with(**task_params)