In watcher/tests/__init__.py has a totally unused,
misleading class so I removed it, as it is never used.
Change-Id: Ib878252453489eb3e1b1ff06f4d6b5e2b0726be5
Closes-Bug: #1549920
Each config option has limitation for type and value.
We make enforce_type=True to check whether we pass wrong type.
Also fixes a type error issue in test_db_manager.py.
Change-Id: I6e111e21588525d32b05eeba75b06583d4e605ed
Related-Bug: #1517839