adding tests for APIRouter

tests/test_api_router.py

@@ -0,0 +1,31 @@
+
+from nicegui import APIRouter, app, ui
+
+from .screen import Screen
+
+
+def test_prefix(screen: Screen):
+    router = APIRouter(prefix='/some-prefix')
+
+    @router.page('/')
+    def page():
+        ui.label('Hello, world!')
+
+    app.include_router(router)
+
+    screen.open('/some-prefix')
+    screen.should_contain('NiceGUI')
+    screen.should_contain('Hello, world!')
+
+
+def test_passing_page_parameters(screen: Screen):
+    router = APIRouter()
+
+    @router.page('/', title='My Custom Title')
+    def page():
+        ui.label('Hello, world!')
+
+    app.include_router(router)
+
+    screen.open('/')
+    screen.should_contain('My Custom Title')