refactor: Avoid redundant lookups in discover.py

src/fastapi_cli/discover.py

@@ -77,25 +77,24 @@ def get_app_name(*, mod_data: ModuleData, app_name: str | None = None) -> str:
         raise FastAPICLIException(
             "Could not import FastAPI, try running 'pip install fastapi'"
         ) from None
-    object_names = dir(mod)
-    object_names_set = set(object_names)
     if app_name:
-        if app_name not in object_names_set:
+        app = getattr(mod, app_name, None)
+        if app is None:
             raise FastAPICLIException(
                 f"Could not find app name {app_name} in {mod_data.module_import_str}"
             )
-        app = getattr(mod, app_name)
         if not isinstance(app, FastAPI):
             raise FastAPICLIException(
                 f"The app name {app_name} in {mod_data.module_import_str} doesn't seem to be a FastAPI app"
             )
         return app_name
-    for preferred_name in ["app", "api"]:
-        if preferred_name in object_names_set:
-            obj = getattr(mod, preferred_name)
-            if isinstance(obj, FastAPI):
-                return preferred_name
-    for name in object_names:
+    for preferred_name in ("app", "api"):
+        obj = getattr(mod, preferred_name, None)
+        if isinstance(obj, FastAPI):
+            return preferred_name
+    for name in dir(mod):
+        if name in ("app", "api"):
+            continue
         obj = getattr(mod, name)
         if isinstance(obj, FastAPI):
             return name

tests/assets/single_file_non_app.py

@@ -0,0 +1,11 @@
+from fastapi import FastAPI
+
+app = "not a FastAPI instance"
+api = 42
+
+my_app = FastAPI()
+
+
+@my_app.get("/")
+def my_app_root():
+    return {"message": "my_app"}

tests/test_utils_single_file.py

@@ -53,6 +53,17 @@ def test_single_file_explicit_object(capsys: CaptureFixture[str]) -> None:
     assert import_data.module_data.module_import_str == "single_file_app"
 
 
+def test_single_file_non_fastapi_app_and_api(capsys: CaptureFixture[str]) -> None:
+    """Fallback walks past non-FastAPI `app`/`api` names to find the real app."""
+    with changing_dir(assets_path):
+        import_data = get_import_data(path=Path("single_file_non_app.py"))
+
+    assert import_data.import_string == "single_file_non_app:my_app"
+
+    assert import_data.module_data.extra_sys_path == assets_path
+    assert import_data.module_data.module_import_str == "single_file_non_app"
+
+
 def test_single_non_existing_file() -> None:
     with changing_dir(assets_path):
         with pytest.raises(FastAPICLIException) as e: