maximize-coverage-of-mysql.go

[CarlosACJ55]

Create table-driven unit tests to cover all of out database-implementation's methods and cover all lines except trivial ones such as error handling.

• [x] Need to add test for OpenID().
• [x] Need to add test for AddUser, GetUser, GetUserID().
• [ ] Suppress unnecessary test logs.
• [ ] Reduce overhead, and unnecessary repetitive operations.