[autotest] Add --autotest_dir to test_that

--autotest_dir allows one to specify a path to a
desired autotest folder instead of using the autotest directory in the
board specific sysroot.

BUG=chromium:272569
TEST=1) Make a copy of autotest directory at /tmp/my_autotest,
2) Insert some logging messages to autoserv and cros_host,
3) Run ./site_utils/test_that.py --autotest_dir=/tmp/my_autotest
   DUT_IP_ADDR dummy_Pass from the source tree.
4) Confirm that the inserted messages are in the log.
   confirm that autotest quickmerge is not run.
5) Run it again from the source tree without
   --autotest_dir option, confirm that autotest quickmerge
   is run and the sysroot version of autotest is used.
6) Run directly from sysroot without --autotest_dir,
   confirm that it works and autotest quickmerge is not run.

Change-Id: I4da8ed0cb04a696eb4127fbe6d12d34551ded81d
Reviewed-on: https://chromium-review.googlesource.com/169764
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Commit-Queue: Fang Deng <fdeng@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
1 file changed