From a user on KnpUniversity.com:
How do you manage testing form validation situations?
For form validation situations, I typically only write 2 scenarios (or sometimes just 1): one that checks that if I submit invalid data, that I see a validation error (I don’t, however assert that all of the validation errors are there – just that the form has some validation errors). Second, I write a scenario that checks a successful form submit.
For me, creating many scenarios to submit a form and check for the different validation errors is over-kill. 99% of the time, adding validation – in Symfony for example – is just one line of code. If we write a scenario for each, we now have one scenario just to test whether or not one line of code is present. For this, I check the validation errors manually – just to make sure I didn’t forget them. I’m not worried about a regression, because it’s highly unlikely that we’ll accidentally remove a line of validation and introduce a bug.