Alternative way to Assert login to a account ?

Scenario is Am suppose to login to a account with following testdata:


Loginname-valid Password-valid ExpectedResult-SUCCESS

Loginname-valid Password-invalid ExpectedResult-Failure

Loginname-invalid Password-valid ExpectedResult-Failure

Now sir lets let go of 1st scenario, consider next 2 scenarios...
If manually i key in testdata as in scenario2, a message check ur credentials for login will be displayed but am not allowed to login.
Same goes for scenario3.

[b:190r6jov]Query:[/b:190r6jov]

Now How do i assert login? Signout button is not displayed for last 2 scenarios.
But [b:190r6jov]can i also Assert using the warning message "check ur credentials for login"?[/b:190r6jov]