Write test cases for Login window to perform Unit testing,Integration testing,System testing,User Acceptapence Testing (one Test Case for each test)

Unit test case will be based on program design or logical flow of Login that will be written by Developer only. It is related to internal structure.Integration test case will include the TC for linking of 2 module.

E.G.:-
On login screen user will user name & pwd. Click on Submit or confirming object so that i/p will get validate into database. So, First integrate chk will be DB connectivity is correct or not. & it recognizing the user name & pwd for comaparision. & Overall o/p will be Login should be successful & Main Screen should be open up.In system-functional testing, Tester will write the test case based on validation of fields & all combination of positive & -ve data. (Valid & Invalid testing)At acceptance level....User will check only for valid & Invalid entry.Test case format changes as per company.