Ask HN: How do you test your app?

Hey guys, how much time you all spend in writing unit test cases?<p>In early stage startups, since application design under goes changes with each iteration, unit test cases needs changes. And it gets harder to keep unit test cases consistent with the code with iterations. Suggestions?<p>Do you think is it OK to burn few initial customers? (if some use cases have not been tested, few customers will face problems)<p>Thoughts?