Re: [Boost-users] [Boost.Test] C++ Unit Tests with Boost.Test, Part 1

Subject: Re: [Boost-users] [Boost.Test] C++ Unit Tests with Boost.Test, Part 1
From: Johan Nilsson (r.johan.nilsson_at_[hidden])
Date: 2009-07-06 02:59:38

[This is actually mainly comments to Part 2]

Richard wrote:
> [Please do not mail me a copy of your followup]
>
> <http://legalizeadulthood.wordpress.com/2009/07/04/c-unit-tests-with-boost-test-part-1/>
>
> In this post, I will describe how to start making unit tests in C++
> with Boost.Test.

I've only glanced through the parts, so I might have missed something. Also 
please note that my comments are very much from a TDD point of view.

In Part 2, you recommend using the CHECK macros by default. Being a 
long-time Boost.Test user (as well as a long-time TDD:er) I strongly believe 
that by default one should always use the REQUIRE variety of the Boost.Test 
macros, for a couple of reasons:

- They most closely correspond to xUnit assertions. TDD:ers are used to 
having their test cases aborted upon an assertion failure.

- When you have multiple verifications per test[*], one of the early 
verifications are quite commonly some kind of precondition/guard statement 
which could lead to memory corruption (or simply useless further testing) if 
the test continues. I know you mention this as a special case in your 
article, but if you use REQUIRE by default you will always be safe.

People will probably object to the above, saying that the want to test 
multiple things in the same test, and want to see the result of all "related 
verifications". Sorry, but I just won't buy that, because:

- You really don't want to manually inspect a lot of numbers/results when 
TDD:ing. Seeing the name of the failing test case should be enough most of 
the time.

- If you really need to see e.g. "x out of y" verifications fail together 
with their output, from a _single_ test case, this is a clear indicator that 
you should split that into multiple (more specific) test cases.

Other than this specific thing, it looks like a good introduction to testing 
with Boost.Test.

Just my 0.02EUR.

/ Johan

[*] As you normally should attempt to stay out of.