There is no time for writing tests
Let’s assume we have decided to increase the stability of our software. So we decide to write tests for our code. The problem is that the customer is requesting new features and deadlines are approaching. Testing will slow us down. We can skip them now and write them later, right?
Wrong. Testing will not slow us down. Also if we decide to skip writing them it’s almost 100% certain that they won’t be written at all.
While tests might slow us down at the begin of the development cycle, the truth is the longer the software needs to be maintained tests will dramatically speed us up.