On Windows, don't try to create relative paths across different drives

test/win/generator-output-different-drive/gyptest-generator-output-different-drive.py

Index: test/win/generator-output-different-drive/gyptest-generator-output-different-drive.py
===================================================================
--- test/win/generator-output-different-drive/gyptest-generator-output-different-drive.py	(revision 0)
+++ test/win/generator-output-different-drive/gyptest-generator-output-different-drive.py	(revision 0)
@@ -0,0 +1,44 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2013 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.
+
+"""
+Test that the generator output can be written to a different drive on Windows.
+"""
+
+import os
+import TestGyp
+import string
+import subprocess
+import sys
+
+
+if sys.platform == 'win32':
+  import win32api
+
+  test = TestGyp.TestGyp(formats=['msvs', 'ninja'])
+
+  def GetFirstFreeDriveLetter():
+    """ Returns the first unused Windows drive letter in [A, Z] """
+    all_letters = [c for c in string.uppercase]
+    in_use = win32api.GetLogicalDriveStrings()
+    free = list(set(all_letters) - set(in_use))
+    return free[0]
+
+  output_dir = os.path.join('different-drive', 'output')
+  if not os.path.isdir(os.path.abspath(output_dir)):
+    os.makedirs(os.path.abspath(output_dir))
+  output_drive = GetFirstFreeDriveLetter()
+  subprocess.call(['subst', '%c:' % output_drive, os.path.abspath(output_dir)])
+  try:
+    test.run_gyp('prog.gyp', '--generator-output=%s' % (
+        os.path.join(output_drive, 'output')))
+    test.build('prog.gyp', test.ALL, chdir=os.path.join(output_drive, 'output'))
+    test.built_file_must_exist('program', chdir=os.path.join(output_drive,
+                                                             'output'),
+                               type=test.EXECUTABLE)
+    test.pass_test()
+  finally:
+    subprocess.call(['subst', '%c:' % output_drive, '/D'])