rename app _exit 2/2 (#16398)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Jirka Borovec <6035284+Borda@users.noreply.github.com>

src/lightning_app/core/flow.py

@@ -1,4 +1,5 @@
 import inspect
+import warnings
 from copy import deepcopy
 from datetime import datetime
 from types import FrameType
@@ -367,11 +368,27 @@ def set_state(self, provided_state: Dict, recurse: bool = True) -> None:
             getattr(self, structure).set_state(state)
 
     def stop(self, end_msg: str = "") -> None:
-        """Private method used to exit the application."""
+        """Method used to exit the application."""
         if end_msg:
             print(end_msg)
         raise ExitAppException
 
+    def _exit(self, end_msg: str = "") -> None:
+        """Used to exit the application.
+
+        Private method.
+
+        .. deprecated:: 1.9.0
+            This function is deprecated and will be removed in 2.0.0. Use :meth:`stop` instead.
+        """
+        warnings.warn(
+            DeprecationWarning(
+                "This function is deprecated and will be removed in 2.0.0. Use `LightningFlow.stop` instead."
+            )
+        )
+
+        return self.stop(end_msg=end_msg)
+
     @staticmethod
     def _is_state_attribute(name: str) -> bool:
         """Every public attribute is part of the state by default and all protected (prefixed by '_') or private

tests/tests_app/core/test_lightning_flow.py

@@ -954,3 +954,9 @@ def run(self):
         assert len(v.component_names) == 1
         assert v.component_names[0][:-1] in ("root.w_list.", "root.w_dict.")
         assert v.component_names[0][-1].isdigit()
+
+
+def test_deprecation_warning_exit():
+    with pytest.raises(ExitAppException):
+        with pytest.warns(DeprecationWarning, match="*Use LightningFlow.stop instead"):
+            RootFlowReady()._exit()