Add a mechanism to scramble Mojo message IDs.

mojo/public/tools/bindings/mojom_bindings_generator_unittest.py

 # Copyright 2014 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.
 
 import unittest
 
 from mojom_bindings_generator import MakeImportStackMessage
+from mojom_bindings_generator import ScrambleMethodOrdinals
+
+
+class FakeIface(object):
+  def __init__( self ):
+    self.name = None
+    self.methods = None
+
+
+class FakeMethod(object):
+  def __init__( self ):
+    self.ordinal = None
+    self.ordinal_comment = None
 
 
 class MojoBindingsGeneratorTest(unittest.TestCase):
   """Tests mojo_bindings_generator."""
 
   def testMakeImportStackMessage(self):
     """Tests MakeImportStackMessage()."""
     self.assertEquals(MakeImportStackMessage(["x"]), "")
     self.assertEquals(MakeImportStackMessage(["x", "y"]),
         "\n  y was imported by x")
     self.assertEquals(MakeImportStackMessage(["x", "y", "z"]),
         "\n  z was imported by y\n  y was imported by x")
 
+  def testScrambleMethodOrdinals(self):
+    """Tests ScrambleMethodOrdinals()."""
+    interface = FakeIface()
+    interface.name = 'RendererConfiguration'
+    interface.methods = [FakeMethod(), FakeMethod(), FakeMethod()]
+    ScrambleMethodOrdinals([interface], "foo")
+    # These next three values are hard-coded. If the generation algorithm
+    # changes from being based on sha256(seed + interface.name + str(i)) then
+    # these numbers will obviously need to change too.
+    #
+    # Note that hashlib.sha256('fooRendererConfiguration1').digest()[:4] is
+    # '\xa5\xbc\xf9\xca' and that hex(1257880741) = '0x4af9bca5'. The
+    # difference in 0x4a vs 0xca is because we only take 31 bits.
+    self.assertEquals(interface.methods[0].ordinal, 1257880741)
+    self.assertEquals(interface.methods[1].ordinal, 631133653)
+    self.assertEquals(interface.methods[2].ordinal, 549336076)
+
 
 if __name__ == "__main__":
   unittest.main()