The beauty of [pattern refactoring](/blog/2019/04/15/pattern-refactoring/) with Rector is transforming thousands of elements at once. Like nuclear chain reaction. But to do it safely, we need a high-quality test to ensure the code still works. Does a high-quality test mean *a lot of* tests? Not necessarily. Instead of writing many tests to cover all our routes, we can write one smart one. How?
