Remove the deprecated pytorch_lightning.core.lightning module (#16318)

Author: carmocca

src/pytorch_lightning/CHANGELOG.md

@@ -143,6 +143,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Removed the deprecated `pytorch_lightning.loops.base` module in favor of `pytorch_lightning.loops.loop` ([#16142](https://github.com/PyTorchLightning/pytorch-lightning/pull/16142))
 
 
+- Removed the deprecated `pytorch_lightning.core.lightning` module in favor of `pytorch_lightning.core.module` ([#16318](https://github.com/PyTorchLightning/pytorch-lightning/pull/16318))
+
+
 - Removed the deprecated `Trainer.reset_train_val_dataloaders()` in favor of `Trainer.reset_{train,val}_dataloader` ([#16131](https://github.com/Lightning-AI/lightning/pull/16131))
 
 

src/pytorch_lightning/_graveyard/core.py

@@ -11,11 +11,27 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import sys
 from typing import Any
 
 from pytorch_lightning import LightningDataModule
 
 
+def _patch_sys_modules() -> None:
+    # TODO: Remove in v2.0.0
+    self = sys.modules[__name__]
+    sys.modules["pytorch_lightning.core.lightning"] = self
+
+
+class LightningModule:
+    # TODO: Remove in v2.0.0
+    def __init__(self, *_: Any, **__: Any) -> None:
+        raise NotImplementedError(
+            "Importing `pytorch_lightning.core.lightning.LightningModule` was deprecated in v1.7.0 and removed as of"
+            " v1.9.0. Please use `from pytorch_lightning import LightningModule` instead"
+        )
+
+
 def _on_save_checkpoint(_: LightningDataModule, __: Any) -> None:
     # TODO: Remove in v2.0.0
     raise NotImplementedError(
@@ -32,6 +48,8 @@ def _on_load_checkpoint(_: LightningDataModule, __: Any) -> None:
     )
 
 
+_patch_sys_modules()
+
 # Methods
 LightningDataModule.on_save_checkpoint = _on_save_checkpoint
 LightningDataModule.on_load_checkpoint = _on_load_checkpoint

src/pytorch_lightning/core/lightning.py

@@ -15,16 +15,6 @@
 import pytest
 
 
-def test_old_lightningmodule_path():
-    from pytorch_lightning.core.lightning import LightningModule
-
-    with pytest.deprecated_call(
-        match="pytorch_lightning.core.lightning.LightningModule has been deprecated in v1.7"
-        " and will be removed in v1.9."
-    ):
-        LightningModule()
-
-
 def test_old_callback_path():
     from pytorch_lightning.callbacks.base import Callback
 

tests/tests_pytorch/deprecated_api/test_remove_1-9.py

@@ -17,6 +17,15 @@
 from pytorch_lightning.demos.boring_classes import BoringDataModule, BoringModel
 
 
+def test_v2_0_0_moved_lightningmodule():
+    from pytorch_lightning.core.lightning import LightningModule
+
+    with pytest.raises(
+        NotImplementedError, match="lightning.LightningModule.*was deprecated in v1.7.0 and removed as of v1.9"
+    ):
+        LightningModule()
+
+
 def test_v2_0_0_unsupported_datamodule_on_save_load_checkpoint():
     datamodule = LightningDataModule()
     with pytest.raises(