how to find test cases for performance scenario code example

Example: scenario testing example

Scenario testing is a software testing
 technique that is based on a scenario.
 Basically It involves converting business
 requirements to test scenarios for better
 understanding and to achieve an end to end testing. 
 
 For Examle :
As  test scenario – “Verify that the user is not
able to login with incorrect credentials”.
Now, we can  brake down into test scenario 
to multiple test cases like-

-Checking that user with correct username and
incorrect password should not be allowed to login.

-Checking that user with incorrect username
and correct password should not be allowed to login.

-Checking that user with incorrect username
and incorrect password should not be allowed to login.