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authorSean Quah <8349537+squahtx@users.noreply.github.com>2022-03-01 13:51:03 +0000
committerGitHub <noreply@github.com>2022-03-01 13:51:03 +0000
commit91bc15c772d22fbe814170ab2e0fdbfa50f9c372 (patch)
treed14ddf85fb4f98c4ce2eaf9d213fb8dc4afbe86d /tests/util/test_async_helpers.py
parentOrder in-flight state group queries in biggest-first order (#11610) (diff)
downloadsynapse-91bc15c772d22fbe814170ab2e0fdbfa50f9c372.tar.xz
Add `stop_cancellation` utility function (#12106)
Diffstat (limited to 'tests/util/test_async_helpers.py')
-rw-r--r--tests/util/test_async_helpers.py45
1 files changed, 45 insertions, 0 deletions
diff --git a/tests/util/test_async_helpers.py b/tests/util/test_async_helpers.py
index cce8d595fc..362014f4cb 100644
--- a/tests/util/test_async_helpers.py
+++ b/tests/util/test_async_helpers.py
@@ -27,6 +27,7 @@ from synapse.logging.context import (
 from synapse.util.async_helpers import (
     ObservableDeferred,
     concurrently_execute,
+    stop_cancellation,
     timeout_deferred,
 )
 
@@ -282,3 +283,47 @@ class ConcurrentlyExecuteTest(TestCase):
         d2 = ensureDeferred(caller())
         d1.callback(0)
         self.successResultOf(d2)
+
+
+class StopCancellationTests(TestCase):
+    """Tests for the `stop_cancellation` function."""
+
+    def test_succeed(self):
+        """Test that the new `Deferred` receives the result."""
+        deferred: "Deferred[str]" = Deferred()
+        wrapper_deferred = stop_cancellation(deferred)
+
+        # Success should propagate through.
+        deferred.callback("success")
+        self.assertTrue(wrapper_deferred.called)
+        self.assertEqual("success", self.successResultOf(wrapper_deferred))
+
+    def test_failure(self):
+        """Test that the new `Deferred` receives the `Failure`."""
+        deferred: "Deferred[str]" = Deferred()
+        wrapper_deferred = stop_cancellation(deferred)
+
+        # Failure should propagate through.
+        deferred.errback(ValueError("abc"))
+        self.assertTrue(wrapper_deferred.called)
+        self.failureResultOf(wrapper_deferred, ValueError)
+        self.assertIsNone(deferred.result, "`Failure` was not consumed")
+
+    def test_cancellation(self):
+        """Test that cancellation of the new `Deferred` leaves the original running."""
+        deferred: "Deferred[str]" = Deferred()
+        wrapper_deferred = stop_cancellation(deferred)
+
+        # Cancel the new `Deferred`.
+        wrapper_deferred.cancel()
+        self.assertTrue(wrapper_deferred.called)
+        self.failureResultOf(wrapper_deferred, CancelledError)
+        self.assertFalse(
+            deferred.called, "Original `Deferred` was unexpectedly cancelled."
+        )
+
+        # Now make the inner `Deferred` fail.
+        # The `Failure` must be consumed, otherwise unwanted tracebacks will be printed
+        # in logs.
+        deferred.errback(ValueError("abc"))
+        self.assertIsNone(deferred.result, "`Failure` was not consumed")