[antlr-interest] gUnit for v4?
parrt at cs.usfca.edu
Sun Apr 15 14:44:28 PDT 2012
Ah. I see that "Dr. Simplify" still awake in Germany. :)
On Apr 15, 2012, at 2:40 PM, Oliver Zeigermann wrote:
> Am 15.04.2012 23:36 schrieb "Terence Parr" <parrt at cs.usfca.edu>:
>> I started down the path of building the new version of gUnit for v4, but
>> I'm beginning to question its value for the new version. Because I am
>> pooh-poohing putting actions directly within a grammar, grammar can only
>> yield parse trees. and looks nice to be able to say:
>> "1" -> (expr 1)
>> "1+2" -> (expr (expr 1) + (expr 2))
>> but so what? all that did was confirm that the parser generated by ANTLR
>> works correctly. it's not telling you anything you didn't know by looking
>> at the grammar.
>> In the old days we used to build ASTs and so we needed to check the
>> structure. That need is no longer here. Also, these rules don't generate
>> output and so we can't check input to output translation.
>> What it comes down to is this: we really need functional testing not unit
>> testing for language applications, unless of course each rule returns a
>> string that the translation of the input some phrase or something. But,
>> it's just as easy to write calls to assertEquals() saying that input x
>> should yield input y. If we are doing something other than generating
>> output, such as building up a data structure, then we really do need to
>> manually check that the data structure is solid given some input.
>> I'm trying to find a flaw in my logic. Is there something I'm missing
>> about testing grammars? In v4, they will give you exactly what you want,
>> unless there is a bug in ANTLR. But that's my problem not yours.
>> If we can't find a major benefit, then we should avoid introducing another
>> moving part to the ANTLR ecosystem.
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