add some simple tests for auto-context

tests/test_auto_context.py

@@ -0,0 +1,21 @@
+from nicegui import ui
+
+from .user import User
+
+
+def test_adding_element_to_index_page(user: User):
+    ui.button('add label', on_click=lambda: ui.label('added'))
+
+    user.open('/')
+    user.click('add label')
+    user.should_see('added')
+
+
+def test_adding_element_to_private_page(user: User):
+    @ui.page('/')
+    def page():
+        ui.button('add label', on_click=lambda: ui.label('added'))
+
+    user.open('/')
+    user.click('add label')
+    user.should_see('added')