Make a slightly better 404 page for pub serve.

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

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 186 matching lines @@
   if (match == null) return false;
   _ports[match[1]] = int.parse(match[2]);
   return true;
 }
 
 void endPubServe() {
   _pubServer.kill();
 }
 
 /// Schedules an HTTP request to the running pub server with [urlPath] and
+/// invokes [callback] with the response.
+///
+/// [root] indicates which server should be accessed, and defaults to "web".
+Future<http.Response> scheduleRequest(String urlPath, {String root}) {
+  return schedule(() {
+    return http.get(_getServerUrlSync(root, urlPath));
+  }, "request $urlPath");
+}
+
+/// Schedules an HTTP request to the running pub server with [urlPath] and
 /// verifies that it responds with a body that matches [expectation].
 ///
 /// [expectation] may either be a [Matcher] or a string to match an exact body.
 /// [root] indicates which server should be accessed, and defaults to "web".
 /// [headers] may be either a [Matcher] or a map to match an exact headers map.
 void requestShouldSucceed(String urlPath, expectation, {String root, headers}) {
-  schedule(() {
-    return http.get(_getServerUrlSync(root, urlPath)).then((response) {
-      if (expectation != null) expect(response.body, expectation);
-      if (headers != null) expect(response.headers, headers);
-    });
-  }, "request $urlPath");
+  scheduleRequest(urlPath, root: root).then((response) {
+    if (expectation != null) expect(response.body, expectation);
+    if (headers != null) expect(response.headers, headers);
+  });
 }
 
 /// Schedules an HTTP request to the running pub server with [urlPath] and
 /// verifies that it responds with a 404.
 ///
 /// [root] indicates which server should be accessed, and defaults to "web".
 void requestShould404(String urlPath, {String root}) {
-  schedule(() {
-    return http.get(_getServerUrlSync(root, urlPath)).then((response) {
-      expect(response.statusCode, equals(404));
-    });
-  }, "request $urlPath");
+  scheduleRequest(urlPath, root: root).then((response) {
+    expect(response.statusCode, equals(404));
+  });
 }
 
 /// 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. [root] indicates which server should be accessed, and defaults to
 /// "web".
 void requestShouldRedirect(String urlPath, redirectTarget, {String root}) {
   schedule(() {
     var request = new http.Request("GET",
         Uri.parse(_getServerUrlSync(root, 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.
 ///
 /// [root] indicates which server should be accessed, and defaults to "web".
 void postShould405(String urlPath, {String root}) {
@@ skipping 157 matching lines @@
 /// included. Unlike [getServerUrl], this should only be called after the ports
 /// are known.
 String _getServerUrlSync([String root, String path]) {
   if (root == null) root = 'web';
   expect(_ports, contains(root));
   var url = "http://127.0.0.1:${_ports[root]}";
   if (path != null) url = "$url/$path";
   return url;
 }