On 12/5/14, 9:42 AM, Chris wrote:
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.
Unit tests are not for detecting bugs. They are only useful for:
1. Making sure things work (a bit).
2. Making sure things continue to work when you refactor or introduce
new code.
3. When a new bug is found you can write a test for it that will make
that bug impossible to ever resurrect.
4. Show how code is supposed to be used.
Again, their purpose is not to detect bugs, but to build more robust
software.
