Introduce mkgrokdump to update tools/v8heapconst.py.

test/mkgrokdump/testcfg.py

Index: test/mkgrokdump/testcfg.py
diff --git a/test/mkgrokdump/testcfg.py b/test/mkgrokdump/testcfg.py
new file mode 100644
index 0000000000000000000000000000000000000000..461c4dfd5ac84d20747d085b649e570d56ba8b34
--- /dev/null
+++ b/test/mkgrokdump/testcfg.py
@@ -0,0 +1,38 @@
+# Copyright 2017 the V8 project authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+
+from testrunner.local import testsuite
+from testrunner.objects import testcase
+
+
+class MkGrokdump(testsuite.TestSuite):
+
+  def __init__(self, name, root):
+    super(MkGrokdump, self).__init__(name, root)
+
+  def ListTests(self, context):
+    test = testcase.TestCase(self, self.shell())
+    return [test]
+
+  def GetFlagsForTestCase(self, testcase, context):
+    return []
+
+  def IsFailureOutput(self, testcase):
+    output = testcase.output
+    v8_path = os.path.dirname(os.path.dirname(os.path.abspath(self.root)))
+    expected_path = os.path.join(v8_path, "tools", "v8heapconst.py")
+    with open(expected_path) as f:
+      expected = f.read()
+    if expected != output.stdout:
+      output.stdout = "Please update tools/v8heapconst.py with the output of mkgrokdump!"
+      return True
+    return False
+
+  def shell(self):
+    return "mkgrokdump"
+
+def GetSuite(name, root):
+  return MkGrokdump(name, root)