[Fix]: fix error and add unit test (#429)

mmengine/hooks/runtime_info_hook.py

@@ -34,7 +34,7 @@ class RuntimeInfoHook(Hook):
         runner.message_hub.update_info('iter', runner.iter)
         runner.message_hub.update_info('max_epochs', runner.max_epochs)
         runner.message_hub.update_info('max_iters', runner.max_iters)
-        if hasattr(runner.train_dataloader.dataset, 'dataset_meta'):
+        if hasattr(runner.train_dataloader.dataset, 'metainfo'):
             runner.message_hub.update_info(
                 'dataset_meta', runner.train_dataloader.dataset.metainfo)
 

tests/test_hooks/test_runtime_info_hook.py

@@ -15,18 +15,32 @@ class TestRuntimeInfoHook(TestCase):
     def test_before_train(self):
         message_hub = MessageHub.get_instance(
             'runtime_info_hook_test_before_train')
+
+        class ToyDataset:
+            ...
+
         runner = Mock()
         runner.epoch = 7
         runner.iter = 71
         runner.max_epochs = 4
         runner.max_iters = 40
         runner.message_hub = message_hub
+        runner.train_dataloader.dataset = ToyDataset()
         hook = RuntimeInfoHook()
         hook.before_train(runner)
         self.assertEqual(message_hub.get_info('epoch'), 7)
         self.assertEqual(message_hub.get_info('iter'), 71)
         self.assertEqual(message_hub.get_info('max_epochs'), 4)
         self.assertEqual(message_hub.get_info('max_iters'), 40)
+        with self.assertRaisesRegex(KeyError, 'dataset_meta is not found'):
+            message_hub.get_info('dataset_meta')
+
+        class ToyDatasetWithMeta:
+            metainfo = dict()
+
+        runner.train_dataloader.dataset = ToyDatasetWithMeta()
+        hook.before_train(runner)
+        self.assertEqual(message_hub.get_info('dataset_meta'), dict())
 
     def test_before_train_epoch(self):
         message_hub = MessageHub.get_instance(