1 files changed, 85 insertions, 0 deletions
diff --git a/tests/util/test_rwlock.py b/tests/util/test_rwlock.py
new file mode 100644
index 0000000000..1d745ae1a7
--- /dev/null
+++ b/tests/util/test_rwlock.py
@@ -0,0 +1,85 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from tests import unittest
+
+from synapse.util.async import ReadWriteLock
+
+
+class ReadWriteLockTestCase(unittest.TestCase):
+
+    def _assert_called_before_not_after(self, lst, first_false):
+        for i, d in enumerate(lst[:first_false]):
+            self.assertTrue(d.called, msg="%d was unexpectedly false" % i)
+
+        for i, d in enumerate(lst[first_false:]):
+            self.assertFalse(
+                d.called, msg="%d was unexpectedly true" % (i + first_false)
+            )
+
+    def test_rwlock(self):
+        rwlock = ReadWriteLock()
+
+        key = object()
+
+        ds = [
+            rwlock.read(key),   # 0
+            rwlock.read(key),   # 1
+            rwlock.write(key),  # 2
+            rwlock.write(key),  # 3
+            rwlock.read(key),   # 4
+            rwlock.read(key),   # 5
+            rwlock.write(key),  # 6
+        ]
+
+        self._assert_called_before_not_after(ds, 2)
+
+        with ds[0].result:
+            self._assert_called_before_not_after(ds, 2)
+        self._assert_called_before_not_after(ds, 2)
+
+        with ds[1].result:
+            self._assert_called_before_not_after(ds, 2)
+        self._assert_called_before_not_after(ds, 3)
+
+        with ds[2].result:
+            self._assert_called_before_not_after(ds, 3)
+        self._assert_called_before_not_after(ds, 4)
+
+        with ds[3].result:
+            self._assert_called_before_not_after(ds, 4)
+        self._assert_called_before_not_after(ds, 6)
+
+        with ds[5].result:
+            self._assert_called_before_not_after(ds, 6)
+        self._assert_called_before_not_after(ds, 6)
+
+        with ds[4].result:
+            self._assert_called_before_not_after(ds, 6)
+        self._assert_called_before_not_after(ds, 7)
+
+        with ds[6].result:
+            pass
+
+        d = rwlock.write(key)
+        self.assertTrue(d.called)
+        with d.result:
+            pass
+
+        d = rwlock.read(key)
+        self.assertTrue(d.called)
+        with d.result:
+            pass