[Cuis-dev] Test error message wrongly formatted

[Martin McClure]

Hi Hernán,

I'm afraid you can't blame Kent Beck for this ambiguity.

#assert:equals: was not in Kent's original SUnit design -- at least it's 
not in his paper from 1999, and it's not in Camp Smalltalk SUnit 3.1 
from 2003.

At GemStone, we have an internal test framework that existed before 
SUnit did, and its primary way of doing assertions is

     self run: aBlock forResult: anObject.

Fifteen years ago or so, Niall Ross was the primary SUnit maintainer, 
and I suggested to him that SUnit could benefit from something like 
#run:forResult:. He didn't think that particular selector fit SUnit's 
way of doing things, but for SUnit 4.0 (2009 or so) he added 
#assert:equals:.

Niall's code did not specify which argument is the expected and which 
the actual. The failure description just says "a is not equal to b." So 
it was left ambiguous.

However, I was never in doubt that the "proper" usage was "assert: 
actual equals: expected." And there's quite a lot of Smalltalk code that 
uses it that way. A random sampling of GemStone's many tests shows 
exactly none that put the expected value first. And Pharo explicitly 
shows which is which, their message pattern in TestAsserter is

    assert: actual equals: expected

and their tests follow that usage.

So, since "we all expect the actual to be first" and there's a quite lot 
of code in Smalltalk-land that agrees with that, I'd suggest that Cuis 
follow suit.

Regards,
-Martin


On 7/23/23 19:29, Hernán Wilkinson via Cuis-dev wrote:
> Hi Hilaire
>  I think all of us that used #assert:equals: had the same feeling as 
> you someday.
>  We all expect the actual to be first, but for some reason I do not 
> know Kent Beck put the expected first when he wrote SUnit and all the 
> descendant testing framework followed that convention (JUnit, NUnit, 
> phpunit, etc etc).
>  We should not change it for historical and compatibility reasons.
>  Adding the message you suggest will not harm, but it is redundant...
>  My advice, give it a couple of days, you will get used to it to put 
> the expected first, it is a matter of time.
>