pkg/shelf: case-insensitive headers, cleaner Request ctor, a lot more tests

pkg/shelf/test/test_util.dart

Index: pkg/shelf/test/test_util.dart
diff --git a/pkg/shelf/test/test_util.dart b/pkg/shelf/test/test_util.dart
index bc1793b7f97dafd892774ab6a97cc9c41ce8be86..a75fab72c9edd5aaa3524fbafc7888ebb2bbd4a3 100644
--- a/pkg/shelf/test/test_util.dart
+++ b/pkg/shelf/test/test_util.dart
@@ -17,7 +17,7 @@ Response syncHandler(Request request, {int statusCode,
     Map<String, String> headers}) {
   if (statusCode == null) statusCode = 200;
   return new Response(statusCode, headers: headers,
-      body: 'Hello from ${request.pathInfo}');
+      body: 'Hello from ${request.url.path}');
 }
 
 /// Calls [syncHandler] and wraps the response in a [Future].
@@ -28,5 +28,6 @@ Future<Response> asyncHandler(Request request) =>
 Future<Response> makeSimpleRequest(Handler handler) =>
     syncFuture(() => handler(_request));
 
-final _request = new Request('/', '', 'GET', '', '1.1',
-    Uri.parse('http://localhost/'), {});
+final _request = new Request('GET', LOCALHOST_URI);
+
+final LOCALHOST_URI = Uri.parse('http://localhost/');