ObjectGraph::RetainingPath

runtime/vm/object_graph_test.cc

 // Copyright (c) 2014, 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 "platform/assert.h"
 #include "vm/object_graph.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
@@ skipping 73 matching lines @@
       graph.IterateObjects(&with);
       Counter without(b_raw, a.raw());
       graph.IterateObjects(&without);
       EXPECT_EQ(2, with.count() - without.count());
       EXPECT_EQ(b_size + c_size,
                 with.size() - without.size());
     }
     EXPECT_EQ(a_size + b_size + c_size + d_size,
               graph.SizeRetainedByInstance(a));
   }
+  {
+    // Get hold of c again.
+    b ^= a.At(0);
+    c ^= b.At(0);
+    b = Array::null();
+    Array& path = Array::Handle(Array::New(2, Heap::kNew));
+    ObjectGraph graph(isolate);
+    // A retaining path should end like this: c <- b <- a <- ...
+    // c itself is not included in the returned path and length.
+    intptr_t length = graph.RetainingPath(&c, path);
+    EXPECT_LE(2, length);
+    Array& expected_b = Array::Handle();
+    expected_b ^= path.At(0);
+    Array& expected_a = Array::Handle();
+    expected_a ^= path.At(1);
+    EXPECT(expected_b.raw() == a.At(0));
+    EXPECT(expected_a.raw() == a.raw());
+  }

[Cutch, 2014/05/20 17:39:12]

What about a test that doesn't have a path?

Also, a test where the Array passed in is too short to hold the path but the
return value from RetainingPath is the true length. That is, pass in an array of
length 0 and then determine the length necessary, and call it a second time to
get the actual path.

[koda, 2014/05/20 20:37:49]

Done.

 }
 
 }  // namespace dart