"What test do we need first? Looking at the list, the first test looks complicated. Start small or not at all. Multiplication, how hard could that be? We'll work on that one first."
The examples like this that were provided were of trivial methods. Trivial can be subjective, but, to me, methods whose bodies are almost always 2-5 lines long, not counting calls to other trivial methods, which may account for maybe another 2-3 additional lines, are basically trivial. It's one thing when you really don't need that much code, but it's another when you have classes upon classes upon classes upon classes, etc. to do something that could be OO and be in two classes with 1/2 as many lines and still be clear.
"Do these steps seem small to you? Remember TDD is not about taking teeny-tiny steps, it's about being able to take teeny-tiny steps. Would I code day-to-day with steps this small? No. But when things get the least bit wierd, I'm glad I can."
This is what Kent meant, but few of us picked up on it, per the first comment to his answer in your example from S.O. and per my experience.
I'm not blaming Kent, Ron, etc. or even saying that they are or were wrong. But, the commonly understood epitome of TDD used to be 100% test coverage and methods for just about everything. Those in the know said more like 60% was better overall but that was not really "true TDD". The implication of 100% "trivial" methods is more overhead for method calls (minor cost, depending, but can be cumulative, increase/decrease call stack size more quickly, which is inefficient), a large number of entry points (more stuff can be null/nil, cause NPE's or need checks if you don't know what is going to call it later, though that can be mitigated somewhat), and just generally too many LOC.
From "Test Driven Development" by Kent Beck, published 2002: http://www.amazon.com/Test-Driven-Development-Kent-Beck/dp/0...
Here are some excerpts:
"What test do we need first? Looking at the list, the first test looks complicated. Start small or not at all. Multiplication, how hard could that be? We'll work on that one first."
The examples like this that were provided were of trivial methods. Trivial can be subjective, but, to me, methods whose bodies are almost always 2-5 lines long, not counting calls to other trivial methods, which may account for maybe another 2-3 additional lines, are basically trivial. It's one thing when you really don't need that much code, but it's another when you have classes upon classes upon classes upon classes, etc. to do something that could be OO and be in two classes with 1/2 as many lines and still be clear.
"Do these steps seem small to you? Remember TDD is not about taking teeny-tiny steps, it's about being able to take teeny-tiny steps. Would I code day-to-day with steps this small? No. But when things get the least bit wierd, I'm glad I can."
This is what Kent meant, but few of us picked up on it, per the first comment to his answer in your example from S.O. and per my experience.
I'm not blaming Kent, Ron, etc. or even saying that they are or were wrong. But, the commonly understood epitome of TDD used to be 100% test coverage and methods for just about everything. Those in the know said more like 60% was better overall but that was not really "true TDD". The implication of 100% "trivial" methods is more overhead for method calls (minor cost, depending, but can be cumulative, increase/decrease call stack size more quickly, which is inefficient), a large number of entry points (more stuff can be null/nil, cause NPE's or need checks if you don't know what is going to call it later, though that can be mitigated somewhat), and just generally too many LOC.