From d20c3465441cd64ba3a1e84ee399bbadc0997bdf Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Tue, 7 Jan 2020 14:09:07 +0000
Subject: [PATCH] port BackgroundUpdateTestCase to HomeserverTestCase (#6653)

---
 changelog.d/6653.misc                   |  1 +
 tests/storage/test_background_update.py | 72 +++++++++++++------------
 2 files changed, 38 insertions(+), 35 deletions(-)
 create mode 100644 changelog.d/6653.misc

diff --git a/changelog.d/6653.misc b/changelog.d/6653.misc
new file mode 100644
index 0000000000..fbe7c0e7db
--- /dev/null
+++ b/changelog.d/6653.misc
@@ -0,0 +1 @@
+Port core background update routines to async/await.
diff --git a/tests/storage/test_background_update.py b/tests/storage/test_background_update.py
index aec76f4ab1..ae14fb407d 100644
--- a/tests/storage/test_background_update.py
+++ b/tests/storage/test_background_update.py
@@ -2,44 +2,37 @@ from mock import Mock
 
 from twisted.internet import defer
 
+from synapse.storage.background_updates import BackgroundUpdater
+
 from tests import unittest
-from tests.utils import setup_test_homeserver
 
 
-class BackgroundUpdateTestCase(unittest.TestCase):
-    @defer.inlineCallbacks
-    def setUp(self):
-        hs = yield setup_test_homeserver(self.addCleanup)
-        self.store = hs.get_datastore()
-        self.clock = hs.get_clock()
+class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
+    def prepare(self, reactor, clock, homeserver):
+        self.updates = self.hs.get_datastore().db.updates  # type: BackgroundUpdater
+        # the base test class should have run the real bg updates for us
+        self.assertTrue(self.updates.has_completed_background_updates())
 
         self.update_handler = Mock()
-
-        yield self.store.db.updates.register_background_update_handler(
+        self.updates.register_background_update_handler(
             "test_update", self.update_handler
         )
 
-        # run the real background updates, to get them out the way
-        # (perhaps we should run them as part of the test HS setup, since we
-        # run all of the other schema setup stuff there?)
-        while True:
-            res = yield self.store.db.updates.do_next_background_update(1000)
-            if res is None:
-                break
-
-    @defer.inlineCallbacks
     def test_do_background_update(self):
-        desired_count = 1000
+        # the time we claim each update takes
         duration_ms = 42
 
+        # the target runtime for each bg update
+        target_background_update_duration_ms = 50000
+
         # first step: make a bit of progress
         @defer.inlineCallbacks
         def update(progress, count):
-            self.clock.advance_time_msec(count * duration_ms)
+            yield self.clock.sleep((count * duration_ms) / 1000)
             progress = {"my_key": progress["my_key"] + 1}
-            yield self.store.db.runInteraction(
+            yield self.hs.get_datastore().db.runInteraction(
                 "update_progress",
-                self.store.db.updates._background_update_progress_txn,
+                self.updates._background_update_progress_txn,
                 "test_update",
                 progress,
             )
@@ -47,37 +40,46 @@ class BackgroundUpdateTestCase(unittest.TestCase):
 
         self.update_handler.side_effect = update
 
-        yield self.store.db.updates.start_background_update(
-            "test_update", {"my_key": 1}
+        self.get_success(
+            self.updates.start_background_update("test_update", {"my_key": 1})
         )
-
         self.update_handler.reset_mock()
-        result = yield self.store.db.updates.do_next_background_update(
-            duration_ms * desired_count
+        res = self.get_success(
+            self.updates.do_next_background_update(
+                target_background_update_duration_ms
+            ),
+            by=0.1,
         )
-        self.assertIsNotNone(result)
+        self.assertIsNotNone(res)
+
+        # on the first call, we should get run with the default background update size
         self.update_handler.assert_called_once_with(
-            {"my_key": 1}, self.store.db.updates.DEFAULT_BACKGROUND_BATCH_SIZE
+            {"my_key": 1}, self.updates.DEFAULT_BACKGROUND_BATCH_SIZE
         )
 
         # second step: complete the update
+        # we should now get run with a much bigger number of items to update
         @defer.inlineCallbacks
         def update(progress, count):
-            yield self.store.db.updates._end_background_update("test_update")
+            self.assertEqual(progress, {"my_key": 2})
+            self.assertAlmostEqual(
+                count, target_background_update_duration_ms / duration_ms, places=0,
+            )
+            yield self.updates._end_background_update("test_update")
             return count
 
         self.update_handler.side_effect = update
         self.update_handler.reset_mock()
-        result = yield self.store.db.updates.do_next_background_update(
-            duration_ms * desired_count
+        result = self.get_success(
+            self.updates.do_next_background_update(target_background_update_duration_ms)
         )
         self.assertIsNotNone(result)
-        self.update_handler.assert_called_once_with({"my_key": 2}, desired_count)
+        self.update_handler.assert_called_once()
 
         # third step: we don't expect to be called any more
         self.update_handler.reset_mock()
-        result = yield self.store.db.updates.do_next_background_update(
-            duration_ms * desired_count
+        result = self.get_success(
+            self.updates.do_next_background_update(target_background_update_duration_ms)
         )
         self.assertIsNone(result)
         self.assertFalse(self.update_handler.called)