Add Uri.replace which creates a new Uri with the same fields as the original, but with some fields …

tests/corelib/uri_test.dart

 // 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 uriTest;
 
 import "package:expect/expect.dart";
 import 'dart:convert';
 
 testUri(String uri, bool isAbsolute) {
@@ skipping 336 matching lines @@
   Expect.equals("//y", uri.path);
   Expect.equals("file:////y", uri.toString());
 
   // File scheme noralizes to always showing authority, even if empty.
   uri = new Uri(scheme: "file", path: "/y");
   Expect.equals("file:///y", uri.toString());
   uri = new Uri(scheme: "file", path: "y");
   Expect.equals("file:///y", uri.toString());
 }
 
+void testReplace() {
+  var uris = [
+    Uri.parse(""),
+    Uri.parse("a://b@c:4/e/f?g#h"),
+    Uri.parse("$SCHEMECHAR://$USERINFOCHAR@$REGNAMECHAR:$DIGIT/$PCHAR/$PCHAR"
+              "?$QUERYCHAR#$QUERYCHAR"),
+  ];
+  for (var uri1 in uris) {
+    for (var uri2 in uris) {
+      if (identical(uri1, uri2)) continue;
+      var scheme = uri1.scheme;
+      var userInfo = uri1.userInfo;
+      var host = uri1.host;
+      var port = uri1.port;
+      var path = uri1.path;
+      var query = uri1.query;
+      var fragment = uri1.fragment;
+
+      var tmp1 = uri1;
+      test() {
+        var tmp2 = new Uri(scheme: scheme, userInfo: userInfo, host: host,
+                           port: port, path: path,
+                           query: query, fragment: fragment);
+        Expect.equals(tmp1, tmp2);
+      }
+
+      test();
+
+      scheme = uri2.scheme;
+      tmp1 = tmp1.replace(scheme: scheme);
+      test();
+
+      userInfo = uri2.userInfo;
+      tmp1 = tmp1.replace(userInfo: userInfo);
+      test();
+
+      host = uri2.host;
+      tmp1 = tmp1.replace(host: host);
+      test();
+
+      port = uri2.port;
+      tmp1 = tmp1.replace(port: port);
+      test();
+
+      path = uri2.path;
+      tmp1 = tmp1.replace(path: path);
+      test();
+
+      query = uri2.query;
+      tmp1 = tmp1.replace(query: query);
+      test();
+
+      fragment = uri2.fragment;
+      tmp1 = tmp1.replace(fragment: fragment);
+      test();
+    }
+  }
+}
+
 main() {
   testUri("http:", true);
   testUri("file://", true);
   testUri("file", false);
   testUri("http://user@example.com:8080/fisk?query=89&hest=silas", true);
   testUri("http://user@example.com:8080/fisk?query=89&hest=silas#fragment",
           false);
   Expect.stringEquals("http://user@example.com/a/b/c?query#fragment",
                       new Uri(
                           scheme: "http",
@@ skipping 144 matching lines @@
   testEncodeDecodeComponent(nonAscii, nonAsciiEncoding);
 
   // Invalid URI - : and @ is swapped, port ("host") should be numeric.
   Expect.throws(
       () => Uri.parse("file://user@password:host/path"),
       (e) => e is FormatException);
 
   testValidCharacters();
   testInvalidUrls();
   testNormalization();
+  testReplace();
 }
 
 String dump(Uri uri) {
   return "URI: $uri\n"
       "  Scheme:    ${uri.scheme} #${uri.scheme.length}\n"
       "  User-info: ${uri.userInfo} #${uri.userInfo.length}\n"
       "  Host:      ${uri.host} #${uri.host.length}\n"
       "  Port:      ${uri.port}\n"
       "  Path:      ${uri.path} #${uri.path.length}\n"
       "  Query:     ${uri.query} #${uri.query.length}\n"
       "  Fragment:  ${uri.fragment} #${uri.fragment.length}\n";
 }