How to write good test cases from srs?

A well documented SRS would generally detail the specific requirements of the Application Under Test (AUT). To write good test cases, one needs to identify the possible scenarios that can be tested on the AUT. These scenarios could be positive or negative scenarios.


For example while testing a login screen, you need to test that authorized users are allowed access. You also need to test that unauthorized users are denied access. Now the SRS would list the requirements for the Login operation like


1. How many failed attempts should the system allow, if any?


2. After completing the number of failed attempts, should a message be displayed, or should the login screen just be closed.





Here are 2 sample scenarios for a failed login itself. In the same manner, it would be ideal for a tester list down all the possible scenarios that could occur based on each of the requirements specified in the SRS.





Once the list of scenarios have been listed, use them and create step by step cases (each step would have a description - action to be performed and an expected result of the action performed) to ensure that that the expected result is obtained.