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<div class="moz-cite-prefix">On 05-10-16 15:20, Moritz Lennert
wrote:<br>
</div>
<blockquote
cite="mid:fddbe68b-1b7e-95ac-8a7e-7317a59a075a@club.worldonline.be"
type="cite">On 05/10/16 14:24, Sören Gebbert wrote:
<br>
<blockquote type="cite">Hi,
<br>
<br>
2016-10-05 10:20 GMT+02:00 Moritz Lennert
<<a class="moz-txt-link-abbreviated" href="mailto:mlennert@club.worldonline.be">mlennert@club.worldonline.be</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:mlennert@club.worldonline.be"><mailto:mlennert@club.worldonline.be></a>>:
<br>
<br>
[sent this from the wrong address, so it didn't get through
to the list]
<br>
<br>
<br>
-------- Message d'origine --------
<br>
Envoyé : 5 octobre 2016 00:41:20 GMT+02:00
<br>
<br>
<br>
<br>
Le 4 octobre 2016 22:55:35 GMT+02:00, "Anna Petrášová"
<br>
<<a class="moz-txt-link-abbreviated" href="mailto:kratochanna@gmail.com">kratochanna@gmail.com</a>
<a class="moz-txt-link-rfc2396E" href="mailto:kratochanna@gmail.com"><mailto:kratochanna@gmail.com></a>> a écrit :
<br>
>On Tue, Oct 4, 2016 at 4:22 PM, Markus Metz
<br>
><<a class="moz-txt-link-abbreviated" href="mailto:markus.metz.giswork@gmail.com">markus.metz.giswork@gmail.com</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:markus.metz.giswork@gmail.com"><mailto:markus.metz.giswork@gmail.com></a>> wrote:
<br>
>> On Tue, Oct 4, 2016 at 5:42 PM, Sören Gebbert
<br>
>> <<a class="moz-txt-link-abbreviated" href="mailto:soerengebbert@googlemail.com">soerengebbert@googlemail.com</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:soerengebbert@googlemail.com"><mailto:soerengebbert@googlemail.com></a>> wrote:
<br>
>>> Hi,
<br>
>>>>
<br>
>>>>
<br>
>>>> >
<br>
>>>> > You are very welcome to write the
missing tests for core modules.
<br>
>>>> >
<br>
>>>> > However, i don't understand the
argument that because many core
<br>
>modules
<br>
>>>> > have
<br>
>>>> > no tests, therefore new modules don't
need them. If developers of
<br>
>addon
<br>
>>>> > module are serious about the attempt
to make their modules usable
<br>
>and
<br>
>>>> > maintainable for others, then they
have to implement tests. Its
<br>
>and
<br>
>>>> > integral
<br>
>>>> > part of the development process and
GRASS has a beautiful test
<br>
>>>> > environment
<br>
>>>> > hat makes writing tests easy. Tests
and documentation are part of
<br>
>coding
<br>
>>>> > and
<br>
>>>> > not something special. I don't think
this is a hard requirement.
<br>
>>>> >
<br>
>>>> > There is a nice statement that is not
far from the truth:
<br>
>Untested code
<br>
>>>> > is
<br>
>>>> > broken code.
<br>
>>>>
<br>
>>>> these gunittests only test if a module
output stays the same. This
<br>
>>>
<br>
>>>
<br>
>>> This is simply wrong, please read the gunittest
documentation.
<br>
>>
<br>
>> but then why does
<br>
>>>
<br>
>>> The gunittest for the v.stream.order addon is
an example how its
<br>
>done:
<br>
>>>
<br>
><a class="moz-txt-link-freetext" href="https://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.stream.order/testsuite/test_stream_order.py">https://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.stream.order/testsuite/test_stream_order.py</a><br>
<a class="moz-txt-link-rfc2396E" href="https://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.stream.order/testsuite/test_stream_order.py"><https://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.stream.order/testsuite/test_stream_order.py></a><br>
>>
<br>
>> assume certain order numbers for features 4 and 7?
What if these
<br>
>order
<br>
>> numbers are wrong?
<br>
>>
<br>
>> Recently I fixed bugs in r.stream.order, related to
stream length
<br>
>> calculations which are in turn used to determine
stream orders. The
<br>
>> gunittest did not pick up 1) the bugs, 2) the bug
fixes.
<br>
>>
<br>
>>>
<br>
>>> You can write gunittests that will test every
flag, every option,
<br>
>their
<br>
>>> combination and any output of a module. I have
implemented plenty of
<br>
>tests,
<br>
>>> that check for correct error handling. Writing
tests is effort, but
<br>
>you have
<br>
>>> to do it anyway. Why not implementing a
gunittest for every feature
<br>
>while
<br>
>>> developing the module?
<br>
>>>>
<br>
>>>>
<br>
>>>> My guess for the r.stream.* modules is at
least 40 man hours of
<br>
>>>> testing to make sure they work correctly.
That includes evaluation
<br>
>of
<br>
>>>> float usage, handling of NULL data,
comparison of results with and
<br>
>>>> without the -m flag. Testing should be done
with both high-res
<br>
>(LIDAR)
<br>
>>>> and low-res (e.g. SRTM) DEMs.
<br>
>>>
<br>
>>>
<br>
>>> Tests can be performed on artificial data that
tests all aspects of
<br>
>the
<br>
>>> algorithm. Tests that show the correctness of
the algorithm for
<br>
>specific
<br>
>>> small cases should be preferred. However, large
data should not be
<br>
>an
<br>
>>> obstacle to write a test.
<br>
>>
<br>
>> I agree, for tests during development, not for
gunittests.
<br>
>>
<br>
>> From the examples I read, gunittests expect a
specific output. If the
<br>
>> expected output (obtained with an assumed correct
version of the
<br>
>> module) is wrong, the gunittest is bogus.
gunittests are ok to make
<br>
>> sure the output does not change, but not ok to make
sure the output
<br>
>is
<br>
>> correct. Two random examples are r.stream.order and
r.univar.
<br>
>
<br>
>
<br>
>I am not sure why are we discussing this, it's pretty
obvious that
<br>
>gunittests can serve to a) test inputs/outputs b) catch
changes in
<br>
>results (whether correct or incorrect) c) test
correctness of results.
<br>
>It just depends how you write them, and yes, for some
modules c) is
<br>
>more difficult to implement than for others.
<br>
<br>
<br>
Well, I agree with Markus that unittests are not a panacea
and that
<br>
we should not fall into the trap of thinking that these
tests will
<br>
guarantee that the results of our modules are correct.
<br>
<br>
<br>
Then i live in a parallel universe. Simple question: How do you
test
<br>
your software? How do you assure the correct functionality of
your
<br>
software? Why is it impossible to implement your approach of
testing in
<br>
a dedicated gunittest? How do you assure software quality, if
you don't
<br>
provide tools so that other developers are able to test your
software
<br>
for correctness? Regression tests are not possible then, because
the
<br>
effect of changes in the core libraries can not be easily
detected in
<br>
modules without tests.
<br>
</blockquote>
<br>
<br>
Please note that I was speaking about unit tests, here. I don't
know how efficient our testing framework is for integration
testing ? Maybe we also need to be clearer about what we
understand by tests during such discussions ?
<br>
<br>
Good discussion, though ! :-)
<br>
<br>
<blockquote type="cite">
<br>
Can you explain to me why the developers of the sophisticated
software
<br>
system VTK [1] implement unit and integration tests for all
software
<br>
components to assure the correct functionality of the framework?
They
<br>
didn't saw the trap? They are delusional to think that tests
assure
<br>
software quality?
<br>
<br>
Why is test driven development [2] an integral part of agile
software
<br>
development approaches like scrum or extreme programming? They
didn't
<br>
saw the trap? They are delusional to think that tests assure
software
<br>
quality?
<br>
<br>
[1] <a class="moz-txt-link-freetext" href="http://www.vtk.org/overview/">http://www.vtk.org/overview/</a>
<br>
[2] <a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Test-driven_development">https://en.wikipedia.org/wiki/Test-driven_development</a>
<br>
<br>
<br>
However, I do agree that these tests are useful in detecting
if any
<br>
changes to the code change the output, thus raising a flag
that the
<br>
developer has to at least take into account.
<br>
<br>
I'll try to write some tests for the OBIA tools when I find
the
<br>
time, although I do agree with Markus that it wouldn't be
useful to
<br>
try to write tests that would cover each and every possible
corner
<br>
case...
<br>
<br>
<br>
Why is it "not useful" to write tests for all cases the software
is
<br>
dedicated to solve? It is indeed a lot of effort, but it is
useful.
<br>
</blockquote>
<br>
I would say the question is rather, first, whether it is at all
possible, and, second, that maybe by thinking that it is, we are
too confident in our tests providing information that they really
aren't trying to provide.
<br>
<br>
But I'm no expert whatsoever, on the topic (I am not a computer
scientist, just a scientist programming some tools with my very
limited capabilities), so I don't want to stretch this discussion
out. I do recommend reading this, though:
<br>
<a class="moz-txt-link-freetext" href="http://www.rbcs-us.com/documents/Why-Most-Unit-Testing-is-Waste.pdf">http://www.rbcs-us.com/documents/Why-Most-Unit-Testing-is-Waste.pdf</a>
<br>
<br>
I also like the table close to the top of
<br>
<br>
<a class="moz-txt-link-freetext" href="http://blog.stevensanderson.com/2009/08/24/writing-great-unit-tests-best-and-worst-practises/">http://blog.stevensanderson.com/2009/08/24/writing-great-unit-tests-best-and-worst-practises/</a>
<br>
<br>
(attached as image)
<br>
<br>
And let's remember that this all started as the question of what
should be required for a module to move from addons to core. The
question, therefore, is to find the right balance between
necessary effort and our desire to offer functionality to users.
This also raises the question of why it would be better for a
given module to be in core, rather than in extensions. We could
also imagine the opposite direction, i.e. move modules from core
to extensions to lighten the work load of maintaining core, while
still offering the same functionalities.
<br>
<br>
IMHO, the largest advantage of having a module in core is that
when someone changes internal library APIs, then generally they
check all of core and modify what needs to, but this is not
necessarily the case for extensions...
<br>
<br>
Maybe we should ask the users of whether this distinction between
modules and core and extensions is really relevant for them, or
whether most are perfectly happy to just install extensions.
<br>
</blockquote>
<br>
Since you are asking :-) , as an user, my main interest is in good
documentation and reproducible examples (which I can than also use
to see if outputs make sense to me as an user). In that respect
there is no inherent difference between core modules and extensions.
What is different is that many (most?) of the core functions are
accessible through the menu. I personally don't find that very
important, especially with the modules tab giving fairly easy access
to extensions, but I can imagine that for new / other users,
especially those more inclined to menu-driven applications, this may
make a difference. <br>
<br>
<blockquote
cite="mid:fddbe68b-1b7e-95ac-8a7e-7317a59a075a@club.worldonline.be"
type="cite">
<br>
Moritz
<br>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
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