how to write the testcase for old password check ?

First test for basic validations
- Test for Blank password
- Test for Strong password

Test for validations against last 3
- Input recently used password
- Input II recently used password
- Input III recently used password
- Input 1/2/3 in different case (to check if password check is case sensitive)
- Input 1/2/3 by appending white spaces (to check if string is picked by trimming white spaces on both sides)
- Input a wrong password, and type duplicate one in the subsequent attempt
- Input 4th oldest password for acceptance