Support index.html in pub serve.

sdk/lib/_internal/pub/test/serve/utils.dart

Index: sdk/lib/_internal/pub/test/serve/utils.dart
diff --git a/sdk/lib/_internal/pub/test/serve/utils.dart b/sdk/lib/_internal/pub/test/serve/utils.dart
index 6ae1e1ffb66644f018f076f1fd827fb0cd52a6b3..ef58d330a2701197292eee3ec0c627edd76585b6 100644
--- a/sdk/lib/_internal/pub/test/serve/utils.dart
+++ b/sdk/lib/_internal/pub/test/serve/utils.dart
@@ -9,6 +9,7 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:http/http.dart' as http;
+import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
@@ -189,6 +190,24 @@ void requestShould404(String urlPath) {
   }, "request $urlPath");
 }
 
+/// Schedules an HTTP request to the running pub server with [urlPath] and
+/// verifies that it responds with a redirect to the given [redirectTarget].
+///
+/// [redirectTarget] may be either a [Matcher] or a string to match an exact
+/// URL.
+void requestShouldRedirect(String urlPath, redirectTarget) {
+  schedule(() {
+    var request = new http.Request("GET",
+        Uri.parse("http://127.0.0.1:$_port/$urlPath"));
+    request.followRedirects = false;
+    return request.send().then((response) {
+      expect(response.statusCode ~/ 100, equals(3));
+
+      expect(response.headers, containsPair('location', redirectTarget));
+    });
+  }, "request $urlPath");
+}
+
 /// Schedules an HTTP POST to the running pub server with [urlPath] and verifies
 /// that it responds with a 405.
 void postShould405(String urlPath) {