Implement bookkeeping of events_at

(I didn't think the effects on regressions through, but this will at least
manifest itself because you cannot mark an issue as "fixed in" a release
in which it occurs. It will also show up once we start displaying "events_at"
in the UI, which should be "soon")

ingest/tests.py

@@ -19,6 +19,8 @@ from .views import BaseIngestAPIView
 
 
 class IngestViewTestCase(DjangoTestCase):
+    # this TestCase started out as focussed on alert-sending, but has grown beyond that. Sometimes simply by extending
+    # existing tests. This is not a problem in itself, but may be slightly confusing if you don't realize that.
 
     def setUp(self):
         # the existence of loud/quiet reflect that parts of this test focusses on alert-sending
@@ -54,6 +56,8 @@ class IngestViewTestCase(DjangoTestCase):
         self.assertTrue(send_new_issue_alert.delay.called)
         self.assertFalse(send_regression_alert.delay.called)
         self.assertFalse(send_unmute_alert.delay.called)
+        self.assertEquals(1, Issue.objects.count())
+        self.assertEquals("\n", Issue.objects.get().events_at)
         self.assertEquals(1, TurningPoint.objects.count())
         self.assertEquals(TurningPointKind.FIRST_SEEN, TurningPoint.objects.first().kind)
 
@@ -227,6 +231,20 @@ class IngestViewTestCase(DjangoTestCase):
                 request,
             )
 
+    def test_ingest_view_stores_events_at(self):
+        request = self.request_factory.post("/api/1/store/")
+
+        event_data = create_event_data()
+        event_data["release"] = "1.0"
+
+        BaseIngestAPIView().process_event(
+            event_data,
+            self.loud_project,
+            request,
+        )
+        self.assertEquals(1, Issue.objects.count())
+        self.assertEquals("1.0\n", Issue.objects.get().events_at)
+
 
 class TimeZoneTesCase(DjangoTestCase):
     """This class contains some tests that formalize my understanding of how Django works; they are not strictly tests

ingest/views.py

@@ -178,7 +178,7 @@ class BaseIngestAPIView(APIView):
             # multiple events with the same event_id "don't happen" (i.e. are the result of badly misbehaving clients)
             raise ValidationError("Event already exists", code="event_already_exists")
 
-        create_release_if_needed(ingested_event.project, event.release, event)
+        release = create_release_if_needed(ingested_event.project, event.release, event)
 
         if issue_created:
             TurningPoint.objects.create(
@@ -225,7 +225,8 @@ class BaseIngestAPIView(APIView):
         issue_pc = get_pc_registry().by_issue[issue.id]
         issue_pc.inc(ingested_event.timestamp, counted_entity=event)
 
-        # TODO bookkeeping of events_at goes here.
+        if release.version + "\n" not in issue.events_at:
+            issue.events_at += release.version + "\n"
         issue.save()