test: add test_infomemory_for_stream

tests/dragonfly/snapshot_test.py

@@ -639,3 +639,34 @@ async def check_flag(key, flag):
 
     await check_flag("key1", 2)
     await check_flag("key2", 123456)
+
+
+@pytest.mark.parametrize("format", FILE_FORMATS)
+@dfly_args({**BASIC_ARGS})
+async def test_infomemory_for_stream(df_factory, format: str):
+    dbfilename = f"dump_{tmp_file_name()}"
+    instance = df_factory.create(dbfilename=dbfilename)
+    instance.start()
+    async_client = instance.client()
+    await async_client.execute_command("XADD test 1 var val1")
+    await async_client.execute_command("XADD test 2 var val2")
+
+    async def assert_stream_mem_not_zero():
+        res = await async_client.execute_command("INFO MEMORY")
+
+        for line in res.splitlines():
+            if line.startswith("type_used_memory_stream"):
+                _, v = line.split(":")
+                assert int(v) != 0
+
+    await assert_stream_mem_not_zero()
+
+    await async_client.execute_command("SAVE", format)
+
+    await async_client.execute_command(
+        "DFLY",
+        "LOAD",
+        f"{dbfilename}.rdb" if format == "RDB" else f"{dbfilename}-summary.dfs",
+    )
+
+    await assert_stream_mem_not_zero()