Add code tests.

Author: antfitch

examples/cookbook/navigation/navigation_basics/lib/main_step1_cupertino.dart

@@ -0,0 +1,41 @@
+import 'package:flutter/cupertino.dart';
+
+// #docregion first-second-routes
+class FirstRoute extends StatelessWidget {
+  const FirstRoute({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return CupertinoPageScaffold(
+      navigationBar: const CupertinoNavigationBar(middle: Text('First Route')),
+      child: Center(
+        child: CupertinoButton(
+          child: const Text('Open route'),
+          onPressed: () {
+            // Navigate to second route when tapped.
+          },
+        ),
+      ),
+    );
+  }
+}
+
+class SecondRoute extends StatelessWidget {
+  const SecondRoute({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return CupertinoPageScaffold(
+      navigationBar: const CupertinoNavigationBar(middle: Text('Second Route')),
+      child: Center(
+        child: CupertinoButton(
+          onPressed: () {
+            // Navigate back to first route when tapped.
+          },
+          child: const Text('Go back!'),
+        ),
+      ),
+    );
+  }
+}
+// #enddocregion first-second-routes

examples/cookbook/navigation/navigation_basics/lib/main_step2_cupertino.dart

@@ -0,0 +1,48 @@
+import 'package:flutter/cupertino.dart';
+
+class FirstRoute extends StatelessWidget {
+  const FirstRoute({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return CupertinoPageScaffold(
+      navigationBar: const CupertinoNavigationBar(middle: Text('First Route')),
+      child: Center(
+        child: CupertinoButton(
+          child: const Text('Open route'),
+          // #docregion first-route-on-pressed
+          // Within the `FirstRoute` widget:
+          onPressed: () {
+            Navigator.push(
+              context,
+              CupertinoPageRoute(builder: (context) => const SecondRoute()),
+            );
+          },
+          // #enddocregion first-route-on-pressed
+        ),
+      ),
+    );
+  }
+}
+
+class SecondRoute extends StatelessWidget {
+  const SecondRoute({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return CupertinoPageScaffold(
+      navigationBar: const CupertinoNavigationBar(middle: Text('Second Route')),
+      child: Center(
+        child: CupertinoButton(
+          // #docregion second-route-on-pressed
+          // Within the SecondRoute widget
+          onPressed: () {
+            Navigator.pop(context);
+          },
+          // #enddocregion second-route-on-pressed
+          child: const Text('Go back!'),
+        ),
+      ),
+    );
+  }
+}

src/content/cookbook/navigation/navigation-basics.md

@@ -322,14 +322,6 @@ class SecondRoute extends StatelessWidget {
 
 {% endtabs %}
 
-
-:::secondary
-You don't need to replace all Material widgets with Cupertino versions
-to use [`CupertinoPageRoute`][]
-since Flutter allows you to mix and match Material and Cupertino widgets
-depending on your needs.
-:::
-
 ## Additional navigation methods
 
 The recipe in this topic shows you one way to navigate to a new screen and