feat: add default document on static file handlers

Author: mtwichel

docs/src/content/docs/basics/static-files.mdx

@@ -82,3 +82,22 @@ Future<HttpServer> run(Handler handler, InternetAddress ip, int port) {
 
 In the above example, we're using `api/static` as our static file directory but
 you can specify a path to any directory for Dart Frog to use.
+
+You can also serve a default document by specifying the `defaultDocument`
+parameter when creating the `createStaticFileHandler` handler.
+
+```dart
+import 'dart:io';
+
+import 'package:dart_frog/dart_frog.dart';
+
+Future<HttpServer> run(Handler handler, InternetAddress ip, int port) {
+  const customStaticFilePath = 'api/static';
+  final cascade = Cascade()
+      .add(createStaticFileHandler(path: customStaticFilePath, defaultDocument: 'index.html'))
+      .add(handler);
+  return serve(cascade.handler, ip, port);
+}
+```
+
+In this example, requests made to the root of the server will serve the `index.html` file.

packages/dart_frog/lib/src/create_static_file_handler.dart

@@ -3,6 +3,11 @@ import 'package:shelf_static/shelf_static.dart';
 
 /// Creates a [Handler] that serves static files within provided [path].
 /// Defaults to the `public` directory.
-Handler createStaticFileHandler({String path = 'public'}) {
-  return fromShelfHandler(createStaticHandler(path));
+Handler createStaticFileHandler({
+  String path = 'public',
+  String? defaultDocument,
+}) {
+  return fromShelfHandler(
+    createStaticHandler(path, defaultDocument: defaultDocument),
+  );
 }

packages/dart_frog/test/src/create_static_file_handler_test.dart

@@ -47,6 +47,46 @@ void main() {
       );
       expect(notFoundResponse.statusCode, equals(HttpStatus.notFound));
 
+      final rootResponse = await http.get(
+        Uri.parse('http://localhost:$port/'),
+      );
+      expect(rootResponse.statusCode, equals(HttpStatus.notFound));
+
+      await server.close();
+      tempDir.delete(recursive: true).ignore();
+    });
+
+    test('serves default document', () async {
+      const port = 3003;
+      final tempDir = Directory.systemTemp.createTempSync();
+
+      const messageContents = 'hello world';
+      File(
+        path.join(tempDir.path, 'message.txt'),
+      ).writeAsStringSync(messageContents);
+
+      final profileContents = json.encode(
+        <String, dynamic>{'name': 'dash', 'age': 42, 'lovesDart': true},
+      );
+      File(
+        path.join(tempDir.path, 'profile.json'),
+      ).writeAsStringSync(profileContents);
+
+      final server = await serve(
+        createStaticFileHandler(
+          path: tempDir.path,
+          defaultDocument: 'message.txt',
+        ),
+        'localhost',
+        port,
+      );
+
+      final messageResponse = await http.get(
+        Uri.parse('http://localhost:$port/'),
+      );
+      expect(messageResponse.statusCode, equals(HttpStatus.ok));
+      expect(messageResponse.body, equals(messageContents));
+
       await server.close();
       tempDir.delete(recursive: true).ignore();
     });