Add ResponseCache tests. (#9458)

tests/util/caches/test_responsecache.py

@@ -0,0 +1,131 @@
+# Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+# 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 synapse.util.caches.response_cache import ResponseCache
+
+from tests.server import get_clock
+from tests.unittest import TestCase
+
+
+class DeferredCacheTestCase(TestCase):
+    """
+    A TestCase class for ResponseCache.
+
+    The test-case function naming has some logic to it in it's parts, here's some notes about it:
+        wait: Denotes tests that have an element of "waiting" before its wrapped result becomes available
+              (Generally these just use .delayed_return instead of .instant_return in it's wrapped call.)
+        expire: Denotes tests that test expiry after assured existence.
+                (These have cache with a short timeout_ms=, shorter than will be tested through advancing the clock)
+    """
+
+    def setUp(self):
+        self.reactor, self.clock = get_clock()
+
+    def with_cache(self, name: str, ms: int = 0) -> ResponseCache:
+        return ResponseCache(self.clock, name, timeout_ms=ms)
+
+    @staticmethod
+    async def instant_return(o: str) -> str:
+        return o
+
+    async def delayed_return(self, o: str) -> str:
+        await self.clock.sleep(1)
+        return o
+
+    def test_cache_hit(self):
+        cache = self.with_cache("keeping_cache", ms=9001)
+
+        expected_result = "howdy"
+
+        wrap_d = cache.wrap(0, self.instant_return, expected_result)
+
+        self.assertEqual(
+            expected_result,
+            self.successResultOf(wrap_d),
+            "initial wrap result should be the same",
+        )
+        self.assertEqual(
+            expected_result,
+            self.successResultOf(cache.get(0)),
+            "cache should have the result",
+        )
+
+    def test_cache_miss(self):
+        cache = self.with_cache("trashing_cache", ms=0)
+
+        expected_result = "howdy"
+
+        wrap_d = cache.wrap(0, self.instant_return, expected_result)
+
+        self.assertEqual(
+            expected_result,
+            self.successResultOf(wrap_d),
+            "initial wrap result should be the same",
+        )
+        self.assertIsNone(cache.get(0), "cache should not have the result now")
+
+    def test_cache_expire(self):
+        cache = self.with_cache("short_cache", ms=1000)
+
+        expected_result = "howdy"
+
+        wrap_d = cache.wrap(0, self.instant_return, expected_result)
+
+        self.assertEqual(expected_result, self.successResultOf(wrap_d))
+        self.assertEqual(
+            expected_result,
+            self.successResultOf(cache.get(0)),
+            "cache should still have the result",
+        )
+
+        # cache eviction timer is handled
+        self.reactor.pump((2,))
+
+        self.assertIsNone(cache.get(0), "cache should not have the result now")
+
+    def test_cache_wait_hit(self):
+        cache = self.with_cache("neutral_cache")
+
+        expected_result = "howdy"
+
+        wrap_d = cache.wrap(0, self.delayed_return, expected_result)
+        self.assertNoResult(wrap_d)
+
+        # function wakes up, returns result
+        self.reactor.pump((2,))
+
+        self.assertEqual(expected_result, self.successResultOf(wrap_d))
+
+    def test_cache_wait_expire(self):
+        cache = self.with_cache("medium_cache", ms=3000)
+
+        expected_result = "howdy"
+
+        wrap_d = cache.wrap(0, self.delayed_return, expected_result)
+        self.assertNoResult(wrap_d)
+
+        # stop at 1 second to callback cache eviction callLater at that time, then another to set time at 2
+        self.reactor.pump((1, 1))
+
+        self.assertEqual(expected_result, self.successResultOf(wrap_d))
+        self.assertEqual(
+            expected_result,
+            self.successResultOf(cache.get(0)),
+            "cache should still have the result",
+        )
+
+        # (1 + 1 + 2) > 3.0, cache eviction timer is handled
+        self.reactor.pump((2,))
+
+        self.assertIsNone(cache.get(0), "cache should not have the result now")