Also test with random tmp files because some tests might fail if
the files they want to write to already exist.

Change-Id: Ia8be496ced6585e4914997975f04760cad5a1012
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: dc0215517fc44451e8fc86f08157ae97eb0d9e39