Do everything in Java…

[Chris via Digitalmars-d]

On Friday, 5 December 2014 at 12:06:55 UTC, Nemanja Boric wrote:
>> The good thing about unit tests is that they tell you when you 
>> break existing code.
>
> That's the great thing about unittests, and the reason why I 
> write unittests. I work on a fairly complex code base and every 
> now and then there's a new feature requested. Implementing 
> features involves several to dozen of modules to be changed, 
> and there's no way that I could guarantee that feature 
> implementation didn't change behaviour of the existing code. I 
> both hate and love when I `make` compiles and unittest fails.
>
>> But you'll realize that soon enough anyway.
>
> This is not good enough for me. Sometimes "soon enough" means 
> week or two before somebody actually notice the bug in the 
> implementation (again, very complex project that's simply not 
> hand-testable), and that's definitively not soon enough keeping 
> in mind amount of $$$ that you wasted into air.
>
>
>
> On Friday, 5 December 2014 at 11:53:11 UTC, Chris wrote:
>> On Friday, 5 December 2014 at 09:27:16 UTC, Paulo  Pinto wrote:
>>> On Friday, 5 December 2014 at 02:25:20 UTC, Walter Bright 
>>> wrote:
>>>> On 12/4/2014 5:32 PM, ketmar via Digitalmars-d wrote:
>>>>>> http://www.teamten.com/lawrence/writings/java-for-everything.html
>>>>> i didn't read the article, but i bet that this is just 
>>>>> another article
>>>>> about his language of preference and how any other language 
>>>>> he tried
>>>>> doesn't have X or Y or Z. and those X, Y and Z are 
>>>>> something like "not
>>>>> being on market for long enough", "vendor ACME didn't 
>>>>> ported ACMElib to
>>>>> it", "out staff is trained in G but not in M" and so on. 
>>>>> boring.
>>>>>
>>>>
>>>> From the article:
>>>>
>>>> "Most importantly, the kinds of bugs that people introduce 
>>>> most often aren’t the kind of bugs that unit tests catch. 
>>>> With few exceptions (such as parsers), unit tests are a 
>>>> waste of time."
>>>>
>>>> Not my experience with unittests, repeated over decades and 
>>>> with different languages. Unit tests are a huge win, even 
>>>> with statically typed languages.
>>>
>>> Yes, but they cannot test everything. GUI code is specially 
>>> ugly as it requires UI automation tooling.
>>>
>>> They do exist, but only enterprise customers are willing to 
>>> pay for it.
>>>
>>> This is why WPF has UI automation built-in.
>>>
>>> The biggest problem with unit tests are managers that want to 
>>> see shiny reports, like those produced by tools like Sonar.
>>>
>>> Teams than spend ridiculous amount of time writing 
>>> superfluous unit tests just to match milestone targets.
>>>
>>> Just because code has tests, doesn't mean the tests are 
>>> testing what they should. But if they reach the magical 
>>> percentage number then everyone is happy.
>>>
>>> --
>>> Paulo
>>
>> Now is the right time to confess. I hardly ever use unit tests 
>> although it's included (and encouraged) in D. Why? When I 
>> write new code I "unit test" as I go along, with
>>
>> debug writefln("result %s", result);
>>
>> and stuff like this. Stupid? Unprofessional? I don't know. It 
>> works. I once started to write unit tests only to find out 
>> that indeed they don't catch bugs, because you only put into 
>> unit tests what you know (or expect) at a given moment (just 
>> like the old writefln()). The bugs I, or other people, 
>> discover later would usually not be caught by unit tests 
>> simply because you write for your own expectations at a given 
>> moment and don't realize that there are millions of other ways 
>> to go astray. So the bugs are usually due to a lack of 
>> imagination or a tunnel vision at the moment of writing code. 
>> This will be reflected in the unit tests as well. So why 
>> bother? You merely enshrine your own restricted and circular 
>> logic in "tests". Which reminds me of maths when teachers 
>> would tell us "And see, it makes perfect sense!", yeah, 
>> because they laid down the rules themselves in the first place.
>>
>> The same goes for comparing your output to some "gold 
>> standard". The program claims to have an accuracy of 98%. 
>> Sure, because you wrote for the gold standard and not for the 
>> real world where it drastically drops to 70%.
>>
>> The good thing about unit tests is that they tell you when you 
>> break existing code. But you'll realize that soon enough 
>> anyway.

Yes, yes, yes. Unit tests can be useful in cases like this. But I 
don't think that they are _the_ way to cope with bugs. It's more 
like "stating the obvious", and bugs are hardly ever obvious, 
else they wouldn't be bugs.

I read some comments in D code on github saying "extend unit test 
to include XYZ". So it's already been tested, it works and it 
will never be added, just like the

debug writeln()

disappears after the code has been thoroughly tested. If there's 
a bug, it's not the XYZ that has been tested but the ZYX nobody 
thought of (or couldn't think of, because it works as unexpected 
on Windows) :-).

Usually you run standard tests anyway to see if the old stuff 
still works as expected. Designing unit tests for each module is 
a bit tedious. And what if you change a function/method? The unit 
tests will break and you have to write new ones or comment them 
out. Blah blah blah.

Maybe people expect too much from unit test. They are just a way 
to test if the program still works as expected in the most 
obvious cases. But they are not a debugging tool.