Add a guess for how tests could work

tests/test_dependency_dev_mode.py

@@ -0,0 +1,21 @@
+from nicegui import __version__
+
+from .screen import Screen
+
+
+def test_dev_mode(screen: Screen) -> None:
+    screen.ui_run_kwargs['development'] = True
+    screen.open('/')
+
+    #! probably doesn't work!
+    screen.should_contain(f'<script src="/_nicegui/{__version__}/static/vue.global.js"></script>')
+    screen.should_contain(f'<script src="/_nicegui/{__version__}/static/quasar.umd.js"></script>')
+
+
+def test_prod_mode(screen: Screen):
+    screen.ui_run_kwargs['development'] = False
+    screen.open('/')
+
+    #! probably doesn't work!
+    screen.should_contain(f'<script src="/_nicegui/{__version__}/static/vue.global.prod.js"></script>')
+    screen.should_contain(f'<script src="/_nicegui/{__version__}/static/quasar.umd.prod.js"></script>')