Don't run windows tests on other platforms

pylib/gyp/generator/ninja_test.py

 #!/usr/bin/env python
 
 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """ Unit tests for the ninja.py file. """
 
 import gyp.generator.ninja as ninja
 import unittest
 import StringIO
 import sys
 import TestCommon
 
 
 class TestPrefixesAndSuffixes(unittest.TestCase):
   def test_BinaryNamesWindows(self):
-    writer = ninja.NinjaWriter('foo', 'wee', '.', '.', 'build.ninja', '.',
-        'build.ninja', 'win')
-    spec = { 'target_name': 'wee' }
-    self.assertTrue(writer.ComputeOutputFileName(spec, 'executable').
-        endswith('.exe'))
-    self.assertTrue(writer.ComputeOutputFileName(spec, 'shared_library').
-        endswith('.dll'))
-    self.assertTrue(writer.ComputeOutputFileName(spec, 'static_library').
-        endswith('.lib'))
+    # These cannot run on non-Windows as they require a VS installation to
+    # correctly handle variable expansion.
+    if sys.platform.startswith('win'):
+      writer = ninja.NinjaWriter('foo', 'wee', '.', '.', 'build.ninja', '.',
+          'build.ninja', 'win')
+      spec = { 'target_name': 'wee' }
+      self.assertTrue(writer.ComputeOutputFileName(spec, 'executable').
+          endswith('.exe'))
+      self.assertTrue(writer.ComputeOutputFileName(spec, 'shared_library').
+          endswith('.dll'))
+      self.assertTrue(writer.ComputeOutputFileName(spec, 'static_library').
+          endswith('.lib'))
 
   def test_BinaryNamesLinux(self):
     writer = ninja.NinjaWriter('foo', 'wee', '.', '.', 'build.ninja', '.',
         'build.ninja', 'linux')
     spec = { 'target_name': 'wee' }
     self.assertTrue('.' not in writer.ComputeOutputFileName(spec,
                                                             'executable'))
     self.assertTrue(writer.ComputeOutputFileName(spec, 'shared_library').
         startswith('lib'))
     self.assertTrue(writer.ComputeOutputFileName(spec, 'static_library').
         startswith('lib'))
     self.assertTrue(writer.ComputeOutputFileName(spec, 'shared_library').
         endswith('.so'))
     self.assertTrue(writer.ComputeOutputFileName(spec, 'static_library').
         endswith('.a'))
 
 if __name__ == '__main__':
   unittest.main()