In an earlier post I had described as to how unit tests are "dogs that should not bark". Meaning that Unit tests run "All Green" as code is added, modified, refactored. When a unit test fails, prompt action is taken to get back to an "All Green" state.
One situation when "silent dogs" should be a serious concern is when the signature of a function is changed. That means unit test for the function is missing. That means TDD was not followed. That means a Defect in the Process.
Another situation is when a defect is discovered while inspecting the code. A little while back I had experience of that.
It was an expression that computed the radius of a circle given the length of a chord and the distance of the midpoint of the arc from the chord. High school stuff. The expression was correctly worked out in the explanatory documentation. But in the code I forgot to divide the expression by 2. I plugged the function into the module and merrily carried on. The defect was found by a member of the team that I was coaching. I asked for comments from the team. The best answer: "The dog did not bark". I had the satisfaction of knowing my coaching had been effective😊
I had not followed TDD. My Process Had been Defective. 😢
Lesson: No matter how simple the algebraic expression, use TDD to implement the function.
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