Make ResolveUri return the correct target_uri for relative base uris.

runtime/vm/uri_test.cc

 // Copyright (c) 2016, 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.
 
 #include "vm/uri.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 TEST_CASE(ParseUri_WithScheme_NoQueryNoUser) {
@@ skipping 544 matching lines @@
                target_uri);
 }
 
 
 // dart:core Uri allows for the base url to be relative (no scheme, no
 // authory, relative path) but this behavior is not in RFC 3986.  We
 // do not implement this.
 TEST_CASE(ResolveUri_RelativeBase_NotImplemented) {
   const char* target_uri;
   EXPECT(!ResolveUri("../r1", "b1/b2", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 
   EXPECT(!ResolveUri("..", "b1/b2", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 
   EXPECT(!ResolveUri("../..", "b1/b2", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 
   EXPECT(!ResolveUri("../../..", "b1/b2", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 
   EXPECT(!ResolveUri("../../../r1", "b1/b2", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 
   EXPECT(!ResolveUri("../r1", "../../b1/b2/b3", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 
   EXPECT(!ResolveUri("../../../r1", "../../b1/b2/b3", &target_uri));
-  EXPECT_STREQ("", target_uri);
+  EXPECT(target_uri == NULL);
 }
 
 
 static const char* TestResolve(const char* base_uri, const char* uri) {
   const char* target_uri;
   EXPECT(ResolveUri(uri, base_uri, &target_uri));
   return target_uri;
 }
 
 
@@ skipping 78 matching lines @@
   EXPECT_STREQ(LH "/a/b/e",  TestResolve(base, "./a/b/c/d/../../e"));
   EXPECT_STREQ(LH "/a/b/e",  TestResolve(base, "../a/b/./c/d/../../e"));
   EXPECT_STREQ(LH "/a/b/e",  TestResolve(base, "./a/b/./c/d/../../e"));
   EXPECT_STREQ(LH "/a/b/e/", TestResolve(base, "./a/b/./c/d/../../e/."));
   EXPECT_STREQ(LH "/a/b/e/", TestResolve(base, "./a/b/./c/d/../../e/./."));
   EXPECT_STREQ(LH "/a/b/e/", TestResolve(base, "./a/b/./c/d/../../e/././."));
   #undef LH
 }
 
 }  // namespace dart