Estimating the number of test cases

Question

Our customer has given us a set of requirments for the project.

Up front they want us to estimate the number of system test cases.

Is there any technique for doing this?

Thanks

Regards, James

Answer 1

I would start with counting the use cases and write one test for each component of the use cases or requirements. That's a good number to start with, however there are so many more variables that will not be known until you actually develop the system and also depends on what the system does.

More often than not, you'll need a lot of unit tests to test your code that the customer will not even be aware of. For example, if they require authentication you might have a unit test to simulate authenticating the user, but you may also want a test to test the encryption you're using to encrypt the password.

The number of unit tests depends mainly on what you are trying to accomplish and is hard to predict up front.

I'd ask your customer to determine what they would like to test if they are asking this up front. Programmers write code given the specification they are provided, this usually includes use case diagrams and functional requirements from where they/you can derive the test cases.

Hope this helps!