Improve flutter_rust_bridge_codegen integrate

frb_codegen/src/library/integration/creator.rs

@@ -1,6 +1,7 @@
 use crate::integration::integrator;
 use crate::integration::integrator::IntegrateConfig;
 use crate::library::commands::flutter::flutter_create;
+use anyhow::ensure;
 use log::{debug, info};
 use std::path::Path;
 use std::{env, fs};
@@ -14,11 +15,20 @@ pub struct CreateConfig {
 
 /// Create a new Flutter + Rust project.
 pub fn create(config: CreateConfig) -> anyhow::Result<()> {
-    debug!("create name={}", config.name);
+    let dart_root = env::current_dir()?.join(&config.name);
+    debug!("create name={} dart_root={dart_root:?}", config.name);
+
+    // This will stop the whole generator and tell the users, so we do not care about testing it
+    // frb-coverage:ignore-start
+    ensure!(
+        !dart_root.exists(),
+        "The target folder {:?} already exists. Please use the `integrate` command in this case",
+        dart_root,
+    );
+    // frb-coverage:ignore-end
 
     flutter_create(&config.name)?;
 
-    let dart_root = env::current_dir()?.join(&config.name);
     env::set_current_dir(&dart_root)?;
 
     remove_unnecessary_files(&dart_root)?;

frb_codegen/src/library/integration/integrator.rs

@@ -106,12 +106,12 @@ fn modify_file(
             let commented_existing_content = existing_content
                 .map(|x| {
                     format!(
-                        "\n\n{}",
+                        "// The original content is temporarily commented out to allow generating a self-contained demo - feel free to uncomment later.\n\n{}\n\n",
                         x.split('\n').map(|line| format!("// {line}")).join("\n")
                     )
                 })
                 .unwrap_or_default();
-            return Some((path, [&src, commented_existing_content.as_bytes()].concat()));
+            return Some((path, [commented_existing_content.as_bytes(), &src].concat()));
             // We do not care about this warning
             // frb-coverage:ignore-start
         }

frb_example/flutter_via_integrate/lib/main.dart

@@ -1,28 +1,4 @@
-import 'package:flutter/material.dart';
-import 'package:flutter_via_integrate/src/rust/api/simple.dart';
-import 'package:flutter_via_integrate/src/rust/frb_generated.dart';
-
-Future<void> main() async {
-  await RustLib.init();
-  runApp(const MyApp());
-}
-
-class MyApp extends StatelessWidget {
-  const MyApp({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return MaterialApp(
-      home: Scaffold(
-        appBar: AppBar(title: const Text('flutter_rust_bridge quickstart')),
-        body: Center(
-          child: Text(
-              'Action: Call Rust `greet("Tom")`\nResult: `${greet(name: "Tom")}`'),
-        ),
-      ),
-    );
-  }
-}
+// The original content is temporarily commented out to allow generating a self-contained demo - feel free to uncomment later.
 
 // import 'package:flutter/material.dart';
 //
@@ -150,3 +126,29 @@ class MyApp extends StatelessWidget {
 //   }
 // }
 //
+
+import 'package:flutter/material.dart';
+import 'package:flutter_via_integrate/src/rust/api/simple.dart';
+import 'package:flutter_via_integrate/src/rust/frb_generated.dart';
+
+Future<void> main() async {
+  await RustLib.init();
+  runApp(const MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(title: const Text('flutter_rust_bridge quickstart')),
+        body: Center(
+          child: Text(
+              'Action: Call Rust `greet("Tom")`\nResult: `${greet(name: "Tom")}`'),
+        ),
+      ),
+    );
+  }
+}