So I had a brief conversation on Twitter with Noah Sussman about testing a software system designed as a "Big Ball Of Mud" (BBOM). We could talk about the technical definition of BBOM, but in practical terms a BBOM is a system where we understand and expect that changing one part of the system is likely to cause unknown and unexpected results in other, unrelated parts of the system. Such systems are notoriously difficult to test, but I have tested them long ago in my career, and I was surprised that Noah hadn't encountered this approach of using a "Golden Image" to accomplish that. Let's assume that we're creating an automated system here. Every part of the procedure I describe can be automated. First you need some tests. And you'll need a test environment. BBOM systems come in many different flavors, so I won't specify a test environment too closely. It might be a clone of the production system, or a version of prod with fewer data. It...
QA is not evil