diff --git a/tests/storage/test_id_generators.py b/tests/storage/test_id_generators.py
index 7a05194653..9b9a183e7f 100644
--- a/tests/storage/test_id_generators.py
+++ b/tests/storage/test_id_generators.py
@@ -182,3 +182,39 @@ class MultiWriterIdGeneratorTestCase(HomeserverTestCase):
self.assertEqual(id_gen.get_positions(), {"master": 8})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 8)
+
+ def test_get_persisted_upto_position(self):
+ """Test that `get_persisted_upto_position` correctly tracks updates to
+ positions.
+ """
+
+ self._insert_rows("first", 3)
+ self._insert_rows("second", 5)
+
+ id_gen = self._create_id_generator("first")
+
+ # Min is 3 and there is a gap between 5, so we expect it to be 3.
+ self.assertEqual(id_gen.get_persisted_upto_position(), 3)
+
+ # We advance "first" straight to 6. Min is now 5 but there is no gap so
+ # we expect it to be 6
+ id_gen.advance("first", 6)
+ self.assertEqual(id_gen.get_persisted_upto_position(), 6)
+
+ # No gap, so we expect 7.
+ id_gen.advance("second", 7)
+ self.assertEqual(id_gen.get_persisted_upto_position(), 7)
+
+ # We haven't seen 8 yet, so we expect 7 still.
+ id_gen.advance("second", 9)
+ self.assertEqual(id_gen.get_persisted_upto_position(), 7)
+
+ # Now that we've seen 7, 8 and 9 we can got straight to 9.
+ id_gen.advance("first", 8)
+ self.assertEqual(id_gen.get_persisted_upto_position(), 9)
+
+ # Jump forward with gaps. The minimum is 11, even though we haven't seen
+ # 10 we know that everything before 11 must be persisted.
+ id_gen.advance("first", 11)
+ id_gen.advance("second", 15)
+ self.assertEqual(id_gen.get_persisted_upto_position(), 11)
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