diff --git a/engine/cyclegan.py b/engine/cyclegan.py
index cacb6f9..80e38aa 100644
--- a/engine/cyclegan.py
+++ b/engine/cyclegan.py
@@ -238,6 +238,7 @@ def run(task, config, logger):
             import traceback
             print(traceback.format_exc())
     elif task == "test":
+        assert config.resume_from is not None
         test_dataset = data.DATASET.build_with(config.data.test.dataset)
         logger.info(f"test with dataset:\n{test_dataset}")
         test_data_loader = idist.auto_dataloader(test_dataset, **config.data.test.dataloader)