Best possible testcase for username password screen

Best possible testcase for username password screen:-

1)It accepts alphanumeric characters along with the special characters. Checks whether only the special characters like _, space, - are allowed.

2)Checks whether the user name entered is available in the data base after the tab key is pressed.

3)Error message thrown for the wrong entry of user name if it is already exist.

4)Password should be case sensitive.

5)Password Reset option should be there or password recovery option should be there if required.

6)Email Confirmation and validation.

7)Enter username with 16 characters and enter
password as 6 characters and click on ?OK?(Please
enter below 15 characters for username)

8)Enter username as 12 characters and enter password
as 3 characters and click on ?OK?(Please enter min 5
characters for password)

9)Check by giving space between username and password.
It should give an error or provide help.

10)username and password field length should be in min 5 to
max 15 alphanumeric characters and case sensitive

11)Check whether u can register for a new account using
registration form by not giving mandatory fields/ by keeping
some fields blank, etc.

12)If user is in second page and select reset it reset the previous page also.
by default reset is enable without writing any text it should be enable after writing all necessary field box available.

13)if user select different password while creating new user and select next then user will get the error message like password doesn't match.