update mypy and error msg

Author: rohitgr7

pytorch_lightning/loops/epoch/training_epoch_loop.py

@@ -41,7 +41,7 @@ class TrainingEpochLoop(loops.Loop[_OUTPUTS_TYPE]):
         max_steps: The maximum number of steps (batches) to process
     """
 
-    def __init__(self, min_steps: Optional[int] = 0, max_steps: int = -1):
+    def __init__(self, min_steps: Optional[int] = 0, max_steps: int = -1) -> None:
         super().__init__()
         if max_steps is None:
             rank_zero_deprecation(
@@ -51,10 +51,10 @@ def __init__(self, min_steps: Optional[int] = 0, max_steps: int = -1):
             max_steps = -1
         elif max_steps < -1:
             raise MisconfigurationException(
-                f"`max_steps` must be a non-negative integer or -1. You passed in {max_steps}."
+                f"`max_steps` must be a non-negative integer or -1 (infinite steps). You passed in {max_steps}."
             )
-        self.min_steps: Optional[int] = min_steps
-        self.max_steps: int = max_steps
+        self.min_steps = min_steps
+        self.max_steps = max_steps
 
         self.global_step: int = 0
         self.batch_progress = BatchProgress()

pytorch_lightning/loops/fit_loop.py

@@ -38,7 +38,7 @@ def __init__(
         self,
         min_epochs: Optional[int] = 1,
         max_epochs: int = 1000,
-    ):
+    ) -> None:
         super().__init__()
         if max_epochs < -1:
             # Allow max_epochs to be zero, since this will be handled by fit_loop.done
@@ -105,7 +105,7 @@ def max_steps(self) -> int:
         return self.epoch_loop.max_steps
 
     @max_steps.setter
-    def max_steps(self, value: Optional[int]) -> None:
+    def max_steps(self, value: int) -> None:
         """Sets the maximum number of steps (forwards to epoch_loop)"""
         # TODO(@awaelchli): This setter is required by debugging connector (fast dev run), should be avoided
         if value is None:
@@ -115,7 +115,9 @@ def max_steps(self, value: Optional[int]) -> None:
             )
             value = -1
         elif value < -1:
-            raise MisconfigurationException(f"`max_steps` must be a non-negative integer or -1. You passed in {value}.")
+            raise MisconfigurationException(
+                f"`max_steps` must be a non-negative integer or -1 (infinite steps). You passed in {value}."
+            )
         self.epoch_loop.max_steps = value
 
     @property

tests/trainer/test_trainer.py

@@ -498,17 +498,17 @@ def test_trainer_max_steps_and_epochs(tmpdir):
 
 
 @pytest.mark.parametrize(
-    "max_epochs,max_steps,incorrect_variable,incorrect_value",
+    "max_epochs,max_steps,incorrect_variable",
     [
-        (-100, -1, "max_epochs", -100),
-        (1, -2, "max_steps", -2),
+        (-100, -1, "max_epochs"),
+        (1, -2, "max_steps"),
     ],
 )
-def test_trainer_max_steps_and_epochs_validation(max_epochs, max_steps, incorrect_variable, incorrect_value):
+def test_trainer_max_steps_and_epochs_validation(max_epochs, max_steps, incorrect_variable):
     """Don't allow max_epochs or max_steps to be less than -1 or a float."""
     with pytest.raises(
         MisconfigurationException,
-        match=f"`{incorrect_variable}` must be a non-negative integer or -1. You passed in {incorrect_value}",
+        match=f"`{incorrect_variable}` must be a non-negative integer or -1",
     ):
         Trainer(max_epochs=max_epochs, max_steps=max_steps)