Add a mock HTTP client class.

pkg/http/lib/src/mock_client.dart

Index: pkg/http/lib/src/mock_client.dart
diff --git a/pkg/http/lib/src/mock_client.dart b/pkg/http/lib/src/mock_client.dart
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+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library mock_client;
+
+import 'dart:io';
+
+import 'base_client.dart';
+import 'base_request.dart';
+import 'request.dart';
+import 'response.dart';
+import 'streamed_response.dart';
+import 'utils.dart';
+
+// TODO(nweiz): once Dart has some sort of Rack- or WSGI-like standard for
+// server APIs, MockClient should conform to it.
+
+/// A mock HTTP client designed for use when testing code that uses
+/// [BaseClient]. This client allows you to define a handler callback for all
+/// requests that are made through it so that you can mock a server without
+/// having to send real HTTP requests.
+class MockClient extends BaseClient {
+  /// The handler for receiving [StreamedRequest]s and sending
+  /// [StreamedResponse]s. Setting this will override [handler].
+  set streamHandler(MockClientStreamHandler fn) => _handler = fn;

[Bob Nystrom, 2012/11/05 20:36:04]

Setters that don't have getters are a design smell for me. I think users expect
to be able to access "properties" that they can modify.

A couple of options:

1. Add getters. That's easy for streamHandler, but a little trickier for
handler.
2. If these aren't properties you actually expect users to mutate, make them
constructor parameters instead.
3. Make them methods.

Thoughts?

[nweiz, 2012/11/05 22:35:16]

Made them constructor parameters.

+  MockClientStreamHandler _handler;
+
+  /// The handler for receiving [Request]s and sending [Response]s. Setting this
+  /// will override [streamHandler].
+  set handler(MockClientHandler fn) {
+    _handler = (baseRequest, bodyStream) {
+      return consumeInputStream(bodyStream).chain((bodyBytes) {
+        var request = new Request(baseRequest.method, baseRequest.url);
+        request.persistentConnection = baseRequest.persistentConnection;
+        request.followRedirects = baseRequest.followRedirects;
+        request.maxRedirects = baseRequest.maxRedirects;
+        mapAddAll(request.headers, baseRequest.headers);
+        request.bodyBytes = bodyBytes;
+        request.finalize();
+
+        return fn(request);
+      }).transform((response) {
+        var stream = new ListInputStream();
+        stream.write(response.bodyBytes);
+        stream.markEndOfStream();
+
+        return new StreamedResponse(
+            stream,
+            response.statusCode,
+            response.contentLength,
+            headers: response.headers,
+            isRedirect: response.isRedirect,
+            persistentConnection: response.persistentConnection,
+            reasonPhrase: response.reasonPhrase);
+      });
+    };
+  }
+
+  /// Sends a request to be handled by [handler].
+  Future<StreamedResponse> send(BaseRequest request) {
+    var bodyStream = request.finalize();
+    var redirectCount = 0;

[Bob Nystrom, 2012/11/05 20:36:04]

Remove this?

[nweiz, 2012/11/05 22:35:16]

Done.

+    return async.chain((_) => _handler(request, bodyStream));
+  }
+}
+
+/// A handler function that receives [StreamedRequest]s and sends
+/// [StreamedResponse]s. Note that [request] will be finalized.
+typedef Future<StreamedResponse> MockClientStreamHandler(
+    BaseRequest request, InputStream bodyStream);
+
+/// A handler function that receives [Request]s and sends [Response]s. Note that
+/// [request] will be finalized.
+typedef Future<Response> MockClientHandler(Request request);