Check the stream position before checking if the cache is empty. (#14639)

An empty cache does not mean the entity has no changed, if
it is earlier than the earliest known stream position return that
the entity *has* changed since the cache cannot accurately
answer that query.

1 files changed, 4 insertions, 3 deletions

diff --git a/tests/util/test_stream_change_cache.py b/tests/util/test_stream_change_cache.py

index 0305741c99..3df053493b 100644
--- a/tests/util/test_stream_change_cache.py
+++ b/tests/util/test_stream_change_cache.py
@@ -144,9 +144,10 @@ class StreamChangeCacheTests(unittest.HomeserverTestCase):
         """
         cache = StreamChangeCache("#test", 1)
 
-        # With no entities, it returns False for the past, present, and future.
-        self.assertFalse(cache.has_any_entity_changed(0))
-        self.assertFalse(cache.has_any_entity_changed(1))
+        # With no entities, it returns True for the past, present, and False for
+        # the future.
+        self.assertTrue(cache.has_any_entity_changed(0))
+        self.assertTrue(cache.has_any_entity_changed(1))
         self.assertFalse(cache.has_any_entity_changed(2))
 
         # We add an entity