new list item valid test completed, even if it doesn't yet pass

src/functional_tests/base.py

@@ -30,4 +30,13 @@ class FunctionalTest(StaticLiveServerTestCase):
                 if time.time() - start_time > MAX_WAIT:
                     raise
                 time.sleep(0.5)
-                
+                
+    def wait_for(self, fn):
+        start_time = time.time()
+        while True:
+            try:
+                return fn()
+            except (AssertionError, WebDriverException):
+                if time.time() - start_time > MAX_WAIT:
+                    raise
+                time.sleep(0.5)