test infrastructure ideas appreciated ...

[Kohei Yoshida]

Hi Michael,

I am happy to see that you and I are on the same term on the majority of the
points. But let me nitpick on a few points below.

> On June 10, 2015 at 6:47 AM Michael Meeks <michael.meeks

> 	So - AFAICS -every- bug-fix is potentially unit-testable - it is just a
> matter of the cost to implement that: "stop world, spend months writing
> large test infrastructure" etc. ;-) is possible just not really
> feasible.

While this is correct in the literal sense of the words, and I fully agree, let
me drill down deeper and add a little bit of clarification.

When I said something was "technically unit-testable", I was implying that
writing a unit test is just a matter of adding a new test case to an existing
test infrastructure.  Saying that everything is technically unit-testable as
long as one is willing to write a new test infra/framework when one doesn't
exist is, while factually correct, would end up confusing the issue, and is
slightly beside the point I was trying to make in my earlier post.

> 	My yard-stick would be that if writing the unit-test takes longer than
> finding & fixing the bug - then we have a problem, 

While I think I agree with the general point you are trying to make here, I
would have to slightly disagree with how you chose to word it.

By this wording, if a bug fix takes a mere 5 minute, or even 30 minute, which
can very well happen especially when a bug is in the area you just refactored,
you have a reason not to write a test if you think writing one would take more
than 30 minutes, which is often the case.

I personally would still spend a few hours writing a test for a bug I fixed in
10 to 30 minutes, because, even if the fix took less than an hour today, the
same fix at some arbitrary point in the future may take days or weeks just
because the code may look totally different by then.  I've personally
experienced that first hand during my Calc core refactoring work, so I know that
can happen in real life.

Anyway, I just wanted to make these points clear. I hope you didn't mind my
nitpicking.

Cheers!

Kohei