Support nullable types in mojom.

mojo/public/tools/bindings/pylib/mojom_tests/parse/lexer_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 imp
 import os.path
 import sys
 import unittest
 
 # Disable lint check for finding modules:
@@ skipping 117 matching lines @@
     self.assertEquals(self._SingleTokenForInput("123.456"),
                       _MakeLexToken("FLOAT_CONST", "123.456"))
     self.assertEquals(self._SingleTokenForInput("\"hello\""),
                       _MakeLexToken("STRING_LITERAL", "\"hello\""))
     self.assertEquals(self._SingleTokenForInput("+"),
                       _MakeLexToken("PLUS", "+"))
     self.assertEquals(self._SingleTokenForInput("-"),
                       _MakeLexToken("MINUS", "-"))
     self.assertEquals(self._SingleTokenForInput("&"),
                       _MakeLexToken("AMP", "&"))
+    self.assertEquals(self._SingleTokenForInput("?"),
+                      _MakeLexToken("QSTN", "?"))
     self.assertEquals(self._SingleTokenForInput("="),
                       _MakeLexToken("EQUALS", "="))
     self.assertEquals(self._SingleTokenForInput("=>"),
                       _MakeLexToken("RESPONSE", "=>"))
     self.assertEquals(self._SingleTokenForInput("("),
                       _MakeLexToken("LPAREN", "("))
     self.assertEquals(self._SingleTokenForInput(")"),
                       _MakeLexToken("RPAREN", ")"))
     self.assertEquals(self._SingleTokenForInput("["),
                       _MakeLexToken("LBRACKET", "["))
@@ skipping 28 matching lines @@
   def _SingleTokenForInput(self, input_string):
     """Gets the single token for the given input string. (Raises an exception if
     the input string does not result in exactly one token.)"""
     toks = self._TokensForInput(input_string)
     assert len(toks) == 1
     return toks[0]
 
 
 if __name__ == "__main__":
   unittest.main()