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/pushimage_unittest.py b/scripts/pushimage_unittest.py
old mode 100755
new mode 100644
index 03a68dd..e7fb761
--- a/scripts/pushimage_unittest.py
+++ b/scripts/pushimage_unittest.py
@@ -1,4 +1,3 @@
-#!/usr/bin/python
 # Copyright (c) 2013 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.
@@ -10,10 +9,7 @@
 import logging
 import mock
 import os
-import sys
 
-sys.path.insert(0, os.path.join(os.path.dirname(os.path.realpath(__file__)),
-                                '..', '..'))
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_test_lib
 from chromite.lib import gs
@@ -232,10 +228,10 @@
     pushimage.main(['--board', 'test.board', '/src', '--yes'])
 
 
-if __name__ == '__main__':
+def main(_argv):
   # Use our local copy of insns for testing as the main one is not
   # available in the public manifest.
   signing.INPUT_INSN_DIR = signing.TEST_INPUT_INSN_DIR
 
   # Run the tests.
-  cros_test_lib.main(level=logging.INFO)
+  cros_test_lib.main(level=logging.INFO, module=__name__)