A software QA engineer walks into a bar. He orders a beer. Orders 0 beers. Orders 99999999999 beers. Orders a lizard. Orders -1 beers.

First real customer walks in and asks where the bathroom is. The bar bursts into flames, killing everyone.

Using symbolic execution to simultaneously test all edge cases is a really powerful idea. DeepState is especially powerful since it'll generate test cases you can use to fix bugs and then use them in your traditional CI tests.