Better error message when a test fail to run.

For example, if a test has an incorrect permission, it'll print out
"Error running test <test_path>" with Exception raised.

Also, remove temp directory if it exists.

BUG=None
TEST=manual
1. Change a unittest's permission, e.g. chmod -x py/rule_unittest.py
2. make test
3. make sure that "Error running test <test_path>" is shown.

Change-Id: Ie50ee01c20aa4e2bb929006c9ecfcf256c29974b
Reviewed-on: https://chromium-review.googlesource.com/189423
Commit-Queue: Dean Liao <deanliao@chromium.org>
Tested-by: Dean Liao <deanliao@chromium.org>
Reviewed-by: Ricky Liang <jcliang@chromium.org>
1 file changed