<i>People also don&#x27;t think that unit tests are constant maintenance and time waster - you change this and then, you need to spend time tweaking tests.</i><p>That&#x27;s why you test interfaces, that you&#x27;ve spent time designing so they don&#x27;t change often. You, <i>or someone else who isn&#x27;t as good as you</i>, can change the internals of a block without updating the tests.<p>Given the choice of working with a dev who knows how to write a bubble sort[1] and a dev doesn&#x27;t but does write tests, I&#x27;d go for the latter.<p>[1] To be honest, if someone in my team even considered writing their own sort function, from memory or by googling, I&#x27;d have a quiet word. Use a library. Preferably a well-tested one.