hi friend,

For such an application, there should be a seperate test case for each scenario.

For example, lets take an Airline Booking Tool.

As a normal user you should not be able to login to the backoffice where the administrator has the access, then when the user (normal user) tries to login, an warning/error message "The access is denied ...", write the same test case for Junior and Administration and in the test case make sure what rights do they need to login as Junior and Administrator .

Hope my answer is clear

Sushma