Add tests for constraints on changing the rule for a room

tests/rest/client/test_room_access_rules.py

@@ -311,6 +311,52 @@ class RoomAccessTestCase(unittest.HomeserverTestCase):
             expected_code=200,
         )
 
+    def test_change_rules(self):
+        """Tests that we can only change the current rule from restricted to
+        unrestricted.
+        """
+        # We can change the rule from restricted to unrestricted.
+        self.change_rule_in_room(
+            room_id=self.restricted_room,
+            new_rule=ACCESS_RULE_UNRESTRICTED,
+            expected_code=200,
+        )
+
+        # We can't change the rule from restricted to direct.
+        self.change_rule_in_room(
+            room_id=self.restricted_room,
+            new_rule=ACCESS_RULE_DIRECT,
+            expected_code=403,
+        )
+
+        # We can't change the rule from unrestricted to restricted.
+        self.change_rule_in_room(
+            room_id=self.unrestricted_room,
+            new_rule=ACCESS_RULE_RESTRICTED,
+            expected_code=403,
+        )
+
+        # We can't change the rule from unrestricted to direct.
+        self.change_rule_in_room(
+            room_id=self.unrestricted_room,
+            new_rule=ACCESS_RULE_DIRECT,
+            expected_code=403,
+        )
+
+        # We can't change the rule from direct to restricted.
+        self.change_rule_in_room(
+            room_id=self.direct_rooms[0],
+            new_rule=ACCESS_RULE_RESTRICTED,
+            expected_code=403,
+        )
+
+        # We can't change the rule from direct to unrestricted.
+        self.change_rule_in_room(
+            room_id=self.direct_rooms[0],
+            new_rule=ACCESS_RULE_UNRESTRICTED,
+            expected_code=403,
+        )
+
     def create_room(self, direct=False, rule=None, expected_code=200):
         content = {
             "is_direct": direct,
@@ -349,6 +395,20 @@ class RoomAccessTestCase(unittest.HomeserverTestCase):
         self.assertEqual(channel.code, 200, channel.result)
         return channel.json_body["rule"]
 
+    def change_rule_in_room(self, room_id, new_rule, expected_code=200):
+        data = {
+            "rule": new_rule,
+        }
+        request, channel = self.make_request(
+            "PUT",
+            "/_matrix/client/r0/rooms/%s/state/%s" % (room_id, ACCESS_RULES_TYPE),
+            json.dumps(data),
+            access_token=self.tok,
+        )
+        self.render(request)
+
+        self.assertEqual(channel.code, expected_code, channel.result)
+
     def send_threepid_invite(self, address, room_id, expected_code=200):
         params = {
             "id_server": "testis",