Add fn

Author: carmocca

tests/trainer/optimization/test_manual_optimization.py

@@ -197,6 +197,11 @@ def training_step(self, batch, batch_idx):
             # avoid returning a value
             super().training_step(batch, batch_idx)
 
+        def training_epoch_end(self, outputs) -> None:
+            # outputs is empty as training_step does not return
+            # and it is not automatic optimization
+            assert len(outputs) == 0
+
     model = TestModel()
     model.val_dataloader = None