Add an ostream operator to Value (based on JSONWriter) so that assertions

base/values.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/values.h"
 
 #include <algorithm>
+#include <ostream>
 
 #include "base/float_util.h"
+#include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 
 namespace {
 
 // Make a deep copy of |node|, but don't include empty lists or dictionaries
 // in the copy. It's possible for this function to return NULL and it
 // expects |node| to always be non-NULL.
 Value* CopyWithoutEmptyChildren(Value* node) {
@@ skipping 1030 matching lines @@
   }
   if (lhs_it != end() || rhs_it != other_list->end())
     return false;
 
   return true;
 }
 
 ValueSerializer::~ValueSerializer() {
 }
 
+std::ostream& operator<<(std::ostream& out, const Value& value) {
+  std::string json;
+  JSONWriter::WriteWithOptions(&value,
+                               JSONWriter::OPTIONS_PRETTY_PRINT,
+                               &json);
+  return out << json;
+}
+
 }  // namespace base