test: cover app and playback controller mixin behavior

tests/app/test_app_progress_periodic_save.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+from auditui.app.progress import AppProgressMixin
+
+
+class DummyPlayback:
+    """Playback stub exposing periodic update method."""
+
+    def __init__(self) -> None:
+        """Initialize call counter."""
+        self.saved_calls = 0
+
+    def update_position_if_needed(self) -> None:
+        """Increment call counter for assertions."""
+        self.saved_calls += 1
+
+
+class DummyProgressApp(AppProgressMixin):
+    """Minimal app host containing playback dependency only."""
+
+    def __init__(self) -> None:
+        """Initialize playback stub."""
+        self.playback = DummyPlayback()
+
+
+def test_save_position_periodically_delegates_to_playback() -> None:
+    """Ensure periodic save method delegates to playback updater."""
+    app = DummyProgressApp()
+    app._save_position_periodically()
+    assert app.playback.saved_calls == 1