Update test_catalyst. (#1134)

Author: jplotts

tests/test_catalyst.py

@@ -141,10 +141,18 @@ def test_mnist(self):
             logdir=logdir,
             num_epochs=num_epochs,
             verbose=False,
-            callbacks=[CheckpointCallback(save_n_best=3, use_runner_logdir=True)]
+            callbacks=[CheckpointCallback(
+                logdir,
+                topk=3,
+                save_best=True,
+                loader_key="valid",
+                metric_key="loss",
+                minimize=True)]
         )
-        
-        with open('./logs/_metrics.json') as f:
+
+        with open('./logs/model.storage.json') as f:
             metrics = json.load(f)
-            self.assertTrue(metrics['train.3']['valid']['loss'] < metrics['train.1']['valid']['loss'])
-            self.assertTrue(metrics['best']['valid']['loss'] < 0.35)
+            storage = metrics['storage']
+            self.assertEqual(3, len(storage))
+            self.assertTrue(storage[0]['metric'] < storage[2]['metric'])
+            self.assertTrue(storage[0]['metric']< 0.35)