Add PRESUBMIT.py warning for contradictory NOTREACHED() use.

PRESUBMIT_test.py

 #!/usr/bin/env python
 # 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.
 
 import glob
 import json
 import os
 import re
 import subprocess
@@ skipping 395 matching lines @@
     self.assertTrue(':1 OS_WINDOWS' in errors[0])
     self.assertTrue('(did you mean OS_WIN?)' in errors[0])
 
   def testValidOSMacroNames(self):
     lines = ['#if defined(%s)' % m for m in PRESUBMIT._VALID_OS_MACROS]
     errors = PRESUBMIT._CheckForInvalidOSMacrosInFile(
         MockInputApi(), MockFile('some/path/foo_platform.cc', lines))
     self.assertEqual(0, len(errors))
 
 
+class CheckContradictoryNotreachedUseTest(unittest.TestCase):
+  def testValid(self):
+    lines = ['{',
+             '  // NOTREACHED();',
+             '  /* NOTREACHED(); */',
+             "  char a = '\\\\', b = '\\0', c = '\\'';",
+             '  char d[] = "NOTREACHED();";',
+             '  NOTREACHED(); // blah',
+             '  /* comment */',
+             '  // line continuation \\',
+             '  still inside comment',
+             '  // comment followed by empty line',
+             '',
+             '  ;; ; ;;;',
+             '}',
+             'switch (i) {',
+             '  case 7: NOTREACHED(); break;',
+             '}']
+    output = PRESUBMIT._CheckContradictoryNotreachedUseInFile(
+        MockInputApi(), MockFile('some/path/foo_platform.cc', lines))
+    self.assertEqual(0, len(output))
+
+  def testInvalid(self):
+    lines = ['{',
+             '  NOTREACHED();',
+             '  return;',
+             '}',
+             '{',
+             '  NOTREACHED();',
+             '  /* */',
+             '  return;',
+             '  /* */',
+             '}',
+             '{',
+             '  NOTREACHED();',
+             '  // trailing space, not a line continuation \\ ',
+             '  return;',
+             '}',
+             'switch (i) {',
+             '  case 7: NOTREACHED(); some_thing(); break;',
+             '}']
+    output = PRESUBMIT._CheckContradictoryNotreachedUseInFile(
+        MockInputApi(), MockFile('some/path/foo_platform.cc', lines))
+    self.assertEqual(4, len(output))
+
+
 class CheckAddedDepsHaveTetsApprovalsTest(unittest.TestCase):
   def testFilesToCheckForIncomingDeps(self):
     changed_lines = [
       '"+breakpad",',
       '"+chrome/installer",',
       '"+chrome/plugin/chrome_content_plugin_client.h",',
       '"+chrome/utility/chrome_content_utility_client.h",',
       '"+chromeos/chromeos_paths.h",',
       '"+components/breakpad",',
       '"+components/nacl/common",',
@@ skipping 217 matching lines @@
                        for (filename, contents, _) in test_data]
 
     for (filename, _, expected_error) in test_data:
       actual_error = PRESUBMIT._GetIDLParseError(input_api, filename)
       self.assertTrue(expected_error in str(actual_error),
                       "'%s' not found in '%s'" % (expected_error, actual_error))
 
 
 if __name__ == '__main__':
   unittest.main()