feat(dart_frog): toShelfMiddleware/toShelfHandler adapters (#97)

Author: felangel

packages/dart_frog/lib/src/shelf_adapters.dart

@@ -15,10 +15,32 @@ Middleware fromShelfMiddleware(shelf.Middleware middleware) {
   };
 }
 
+/// Convert from [Middleware] into [shelf.Middleware].
+shelf.Middleware toShelfMiddleware(Middleware middleware) {
+  return (innerHandler) {
+    return (request) async {
+      final response = await middleware((context) async {
+        final response = await innerHandler(context.request._request);
+        return Response._(response);
+      })(RequestContext._(request));
+      return response._response;
+    };
+  };
+}
+
 /// Convert from a [shelf.Handler] into a [Handler].
 Handler fromShelfHandler(shelf.Handler handler) {
   return (context) async {
     final response = await handler(context.request._request);
     return Response._(response);
   };
 }
+
+/// Convert from a [Handler] into a [shelf.Handler].
+shelf.Handler toShelfHandler(Handler handler) {
+  return (request) async {
+    final context = RequestContext._(request);
+    final response = await handler.call(context);
+    return response._response;
+  };
+}

packages/dart_frog/test/src/shelf_adapters_test.dart

@@ -1,8 +1,10 @@
 import 'dart:io';
 
+import 'package:dart_frog/dart_frog.dart';
 import 'package:dart_frog/src/_internal.dart';
 import 'package:http/http.dart' as http;
 import 'package:shelf/shelf.dart' as shelf;
+import 'package:shelf/shelf_io.dart' as shelf_io;
 import 'package:test/test.dart';
 
 void main() {
@@ -20,6 +22,24 @@ void main() {
     });
   });
 
+  group('toShelfHandler', () {
+    test('converts a Handler into a shelf.Handler', () async {
+      Future<Response> handler(RequestContext context) async {
+        return Response(body: 'Hello World');
+      }
+
+      final server = await shelf_io.serve(
+        toShelfHandler(handler),
+        'localhost',
+        8001,
+      );
+      final response = await http.get(Uri.parse('http://localhost:8001'));
+      expect(response.statusCode, equals(HttpStatus.ok));
+      expect(response.body, equals('Hello World'));
+      await server.close();
+    });
+  });
+
   group('fromShelfMiddleware', () {
     test('converts a shelf.Middleware into a Middleware', () async {
       shelf.Handler middleware(shelf.Handler handler) {
@@ -35,12 +55,42 @@ void main() {
           .addMiddleware(fromShelfMiddleware(middleware))
           .addHandler((_) => Response(body: 'Hello World'));
 
-      final server = await serve(handler, 'localhost', 8001);
-      var response = await http.get(Uri.parse('http://localhost:8001'));
+      final server = await serve(handler, 'localhost', 8002);
+      var response = await http.get(Uri.parse('http://localhost:8002'));
+      expect(response.statusCode, equals(HttpStatus.ok));
+      expect(response.body, equals('Hello World'));
+      response = await http.get(
+        Uri.parse('http://localhost:8002').replace(
+          queryParameters: const <String, String>{'foo': 'bar'},
+        ),
+      );
+      expect(response.statusCode, equals(HttpStatus.badRequest));
+      expect(response.body, equals('oops!'));
+      await server.close();
+    });
+  });
+
+  group('toShelfMiddleware', () {
+    test('converts a Middleware into a shelf.Middleware', () async {
+      Handler middleware(Handler handler) {
+        return (context) {
+          if (context.request.url.queryParameters.containsKey('foo')) {
+            return Response(statusCode: HttpStatus.badRequest, body: 'oops!');
+          }
+          return handler(context);
+        };
+      }
+
+      final handler = const shelf.Pipeline()
+          .addMiddleware(toShelfMiddleware(middleware))
+          .addHandler((_) => shelf.Response.ok('Hello World'));
+
+      final server = await shelf_io.serve(handler, 'localhost', 8003);
+      var response = await http.get(Uri.parse('http://localhost:8003'));
       expect(response.statusCode, equals(HttpStatus.ok));
       expect(response.body, equals('Hello World'));
       response = await http.get(
-        Uri.parse('http://localhost:8001').replace(
+        Uri.parse('http://localhost:8003').replace(
           queryParameters: const <String, String>{'foo': 'bar'},
         ),
       );