add some tests

tests/handlers/test_oauth_delegation.py

@@ -491,6 +491,68 @@ class MSC3861OAuthDelegation(HomeserverTestCase):
         error = self.get_failure(self.auth.get_user_by_req(request), SynapseError)
         self.assertEqual(error.value.code, 503)
 
+    def test_introspection_token_cache(self) -> None:
+        access_token = "open_sesame"
+        self.http_client.request = simple_async_mock(
+            return_value=FakeResponse.json(
+                code=200,
+                payload={"active": "true", "scope": "guest", "jti": access_token},
+            )
+        )
+
+        # first call should cache response - check cache
+        # Mpyp ignores below are due to mypy not understanding the dynamic substitution of msc3861 auth code
+        # for regular auth code via the config
+        self.get_success(
+            self.auth._introspect_token(access_token)  # type: ignore[attr-defined]
+        )
+        introspection_token = self.auth._token_cache.get(access_token)  # type: ignore[attr-defined]
+        self.assertEqual(introspection_token["jti"], access_token)
+        # there's been one http request
+        self.http_client.request.assert_called_once()
+
+        # second call should pull from cache, there should still be only one http request
+        token = self.get_success(self.auth._introspect_token(access_token))  # type: ignore[attr-defined]
+        self.http_client.request.assert_called_once()
+        self.assertEqual(token["jti"], access_token)
+
+        # advance past five minutes and check that cache expired - there should be more than one http call now
+        self.reactor.advance(360)
+        token_2 = self.get_success(self.auth._introspect_token(access_token))  # type: ignore[attr-defined]
+        self.assertEqual(self.http_client.request.call_count, 2)
+        self.assertEqual(token_2["jti"], access_token)
+
+        # test that if a cached token is expired, a fresh token will be pulled from authorizing server - first add a
+        # token with a soon-to-expire `exp` field to the cache
+        self.http_client.request = simple_async_mock(
+            return_value=FakeResponse.json(
+                code=200,
+                payload={
+                    "active": "true",
+                    "scope": "guest",
+                    "jti": "stale",
+                    "exp": self.clock.time_msec() + 100,
+                },
+            )
+        )
+        self.get_success(
+            self.auth._introspect_token("stale")  # type: ignore[attr-defined]
+        )
+        introspection_token = self.auth._token_cache.get("stale")  # type: ignore[attr-defined]
+        self.assertEqual(introspection_token["jti"], "stale")
+        self.assertEqual(self.http_client.request.call_count, 1)
+
+        # advance the reactor past the token expiry but less than the cache expiry
+        self.reactor.advance(30)
+        self.assertEqual(self.auth._token_cache.get("stale"), introspection_token)  # type: ignore[attr-defined]
+
+        # check that the next call causes another http request (which will fail because the token is technically expired
+        # but the important thing is we discard the token from the cache and try the network)
+        self.get_failure(
+            self.auth._introspect_token("stale"), InvalidClientTokenError  # type: ignore[attr-defined]
+        )
+        self.assertEqual(self.http_client.request.call_count, 2)
+
     def make_device_keys(self, user_id: str, device_id: str) -> JsonDict:
         # We only generate a master key to simplify the test.
         master_signing_key = generate_signing_key(device_id)