Add unit test for experiment_runner.py

BUG=None
TEST=Ran unittest.

Change-Id: I13b2822f57f4201c94215c603a60f12755230f71
Reviewed-on: https://chrome-internal-review.googlesource.com/163833
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Commit-Queue: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
3 files changed