Refactor the python system_impl module.

mojo/PRESUBMIT_test.py

 #!/usr/bin/env python
 # 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 os
 import sys
 import unittest
 
 import PRESUBMIT
@@ skipping 183 matching lines @@
   def testNakedSourceSetInSDKBuildFile(self):
     """Tests that a source_set within an SDK buildfile is flagged."""
     mock_input_api = self.inputApiContainingFileWithSourceSets(
         _SDK_BUILD_FILE,
         [ 'mojo_sdk_source_set(', 'source_set(' ])
     warnings = PRESUBMIT._BuildFileChecks(mock_input_api, MockOutputApi())
 
     self.assertEqual(1, len(warnings))
     self.checkWarningWithSingleItem(warnings[0], 'SDK', _SDK_BUILD_FILE, 2)
 
+  def testPythonSourceSetInSDKBuildFile(self):
+    """Tests that a python_binary_source_set within an SDK buildfile is
+    accepted."""
+    mock_input_api = self.inputApiContainingFileWithSourceSets(
+        _SDK_BUILD_FILE,
+        [ 'mojo_sdk_source_set(', 'python_binary_source_set(' ])
+    warnings = PRESUBMIT._BuildFileChecks(mock_input_api, MockOutputApi())
+
+    self.assertEqual(0, len(warnings))
+
   def testEDKSourceSetInSDKBuildFile(self):
     """Tests that a mojo_edk_source_set within an SDK buildfile is flagged."""
     mock_input_api = self.inputApiContainingFileWithSourceSets(
         _SDK_BUILD_FILE,
         [ 'mojo_sdk_source_set(', 'mojo_edk_source_set(' ])
     warnings = PRESUBMIT._BuildFileChecks(mock_input_api, MockOutputApi())
 
     self.assertEqual(1, len(warnings))
     self.checkWarningWithSingleItem(warnings[0], 'SDK', _SDK_BUILD_FILE, 2)
 
@@ skipping 20 matching lines @@
   def testIrrelevantBuildFile(self):
     """Tests that a source_set in a non-SDK/EDK buildfile isn't flagged."""
     mock_input_api = self.inputApiContainingFileWithSourceSets(
         _IRRELEVANT_BUILD_FILE,
         [ 'source_set(' ])
     warnings = PRESUBMIT._BuildFileChecks(mock_input_api, MockOutputApi())
     self.assertEqual(0, len(warnings))
 
 if __name__ == '__main__':
   unittest.main()