[App] Hot Fix: Missing root flow in app.flows (#15531)

(cherry picked from commit 1824ad0)

Author: tchaton

src/lightning_app/CHANGELOG.md

@@ -49,7 +49,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 - Fixed writing app name and id in connect.txt file for the command CLI ([#15443](https://github.com/Lightning-AI/lightning/pull/15443))
 
--
+- Fixed missing root flow among the flows of the app ([#15531](https://github.com/Lightning-AI/lightning/pull/15531))
 
 -
 

src/lightning_app/core/app.py

@@ -284,7 +284,7 @@ def check_error_queue(self) -> None:
     @property
     def flows(self) -> List["LightningFlow"]:
         """Returns all the flows defined within this application."""
-        return list(self.root.flows.values())
+        return [self.root] + list(self.root.flows.values())
 
     @property
     def works(self) -> List[LightningWork]:

tests/tests_app/core/test_lightning_app.py

@@ -219,6 +219,7 @@ def test_nested_component_names():
 
 def test_get_component_by_name():
     app = LightningApp(A())
+    assert app.root in app.flows
     assert app.get_component_by_name("root") is app.root
     assert app.get_component_by_name("root.b") is app.root.b
     assert app.get_component_by_name("root.w_a") is app.root.w_a

tests/tests_app/utilities/test_load_app.py

@@ -30,6 +30,7 @@ def test_extract_metadata_from_component():
     app = load_app_from_file(os.path.join(test_script_dir, "app_metadata.py"))
     metadata = extract_metadata_from_app(app)
     assert metadata == [
+        {"affiliation": ["root"], "cls_name": "RootFlow", "module": "__main__", "docstring": "RootFlow."},
         {
             "affiliation": ["root", "flow_a_1"],
             "cls_name": "FlowA",
@@ -41,7 +42,7 @@ def test_extract_metadata_from_component():
             "cls_name": "WorkA",
             "module": "__main__",
             "docstring": "WorkA.",
-            "local_build_config": {"__build_config__": ANY},
+            "local_build_config": {"__build_config__": {"requirements": [], "dockerfile": [], "image": None}},
             "cloud_build_config": {"__build_config__": {"requirements": [], "dockerfile": [], "image": None}},
             "cloud_compute": {
                 "type": "__cloud_compute__",