unittests: cut over to the new wrapper

Now that we have a wrapper to deal with the namespace munging, we can
clean up all our unittests.  This means:
 - add a wrapper symlink for all the unittests
 - drop the +x bits on the direct .py file
 - drop the shebang on the direct .py file
 - delete the manual sys.path munging
 - move the mock import to the common system import path
 - delete unused os/sys imports
 - delete most manual calls to cros_test_lib.main
 - add a main() for the few complicated cros_test_lib.main calls

BUG=chromium:219660
TEST=ran all the unittests

Change-Id: I85614c301e48c86a0ca4201c2b60349d2d488e52
Reviewed-on: https://chromium-review.googlesource.com/233832
Reviewed-by: David James <davidjames@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cros_generate_sysroot_unittest.py b/scripts/cros_generate_sysroot_unittest.py
old mode 100755
new mode 100644
index 50e5e45..fcb5e30
--- a/scripts/cros_generate_sysroot_unittest.py
+++ b/scripts/cros_generate_sysroot_unittest.py
@@ -1,4 +1,3 @@
-#!/usr/bin/python
 # Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -7,11 +6,9 @@
 
 from __future__ import print_function
 
+import mock
 import os
-import sys
 
-sys.path.insert(0, os.path.join(os.path.dirname(os.path.realpath(__file__)),
-                                '..', '..'))
 from chromite.cbuildbot import constants
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_test_lib
@@ -19,10 +16,6 @@
 from chromite.lib import osutils
 from chromite.lib import partial_mock
 
-# TODO(build): Finish test wrapper (http://crosbug.com/37517).
-# Until then, this has to be after the chromite imports.
-import mock
-
 
 Dir = cros_test_lib.Directory
 
@@ -103,7 +96,3 @@
          constants.CHROME_CP])
     self.assertRaises(cros_build_lib.DieSystemExit,
                       cros_gen.FinishParsing, options)
-
-
-if __name__ == '__main__':
-  cros_test_lib.main()