[GRASS-dev] Upcoming 7.2.0: review which addons to move to core

Tue Oct 4 14:02:39 PDT 2016

2016-10-04 22:22 GMT+02:00 Markus Metz <markus.metz.giswork at gmail.com>:

> On Tue, Oct 4, 2016 at 5:42 PM, Sören Gebbert
> <soerengebbert at googlemail.com> wrote:
> > Hi,
> >>
> >>
> >> >
> >> > You are very welcome to write the missing tests for core modules.
> >> >
> >> > However, i don't understand the argument that because many core
> modules
> >> > have
> >> > no tests, therefore new modules don't need them. If developers of
> addon
> >> > module are serious about the attempt to make their modules usable and
> >> > maintainable for others, then they have to implement tests. Its and
> >> > integral
> >> > part of the development process and GRASS has a beautiful test
> >> > environment
> >> > hat makes writing tests easy. Tests and documentation are part of
> coding
> >> > and
> >> > not something special. I don't think this is a hard requirement.
> >> >
> >> > There is a nice statement that is not far from the truth: Untested
> code
> >> > is
> >> > broken code.
> >>
> >> these gunittests only test if a module output stays the same. This
> >
> >
> > This is simply wrong, please read the gunittest documentation.
>
> but then why does
> >
> > The gunittest for the v.stream.order addon is an example how its done:
> > https://trac.osgeo.org/grass/browser/grass-addons/grass7/
> vector/v.stream.order/testsuite/test_stream_order.py
>
> assume certain order numbers for features 4 and 7? What if these order
> numbers are wrong?
>

The checked order numbers are validated by hand. The test example is based
on artificial data, that i have created, for which i know what the correct
order numbers are. Hence i can test if certain features have specific order
numbers, since i know the correct solution.

>
> Recently I fixed bugs in r.stream.order, related to stream length
> calculations which are in turn used to determine stream orders. The
> gunittest did not pick up 1) the bugs, 2) the bug fixes.
>

Then better test implementations are required that checks for correct
output. If a bug was found a test should be written to check the bugfix.
Have a look at this commit that adds two new tests to validate the provided
bugfix:

https://trac.osgeo.org/grass/changeset/69586

A one line bugfix and 50 lines of test code. :)

>
> >
> > You can write gunittests that will test every flag, every option, their
> > combination and any output of a module. I have implemented plenty of
> tests,
> > that check for correct error handling. Writing tests is effort, but you
> have
> > to do it anyway. Why not implementing a gunittest for every feature while
> > developing the module?
> >>
> >>
> >> My guess for the r.stream.* modules is at least 40 man hours of
> >> testing to make sure they work correctly. That includes evaluation of
> >> float usage, handling of NULL data, comparison of results with and
> >> without the -m flag. Testing should be done with both high-res (LIDAR)
> >> and low-res (e.g. SRTM) DEMs.
> >
> >
> > Tests can be performed on artificial data that tests all aspects of the
> > algorithm. Tests that show the correctness of the algorithm for specific
> > small cases should be preferred. However, large data should not be an
> > obstacle to write a test.
>
> I agree, for tests during development, not for gunittests.
>
> From the examples I read, gunittests expect a specific output. If the
> expected output (obtained with an assumed correct version of the
> module) is wrong, the gunittest is bogus. gunittests are ok to make
> sure the output does not change, but not ok to make sure the output is
> correct. Two random examples are r.stream.order and r.univar.
>

I don't understand your argument here or i have a principal problem in
understanding the test topic.

You have to implement a test that checks for correct output, this is the
meaning of a test. You have to design a test scenario from which you know
what the correct solution is and then you test for the correct solution.
What is with r.univar? Create a test map with a specific number of cells
with specific values and test if r.univar is able to compute the correct
values that you have validated by hand.

-- what is the mean, min and max of 10 cells each with value 5? Its 5! --

The most simple check for that is the raster range check in gunittest. If
you know what the range of the resulting raster map has to be, then you can
test for it. If this is not enough then you can check against the
uni-variate statistic output of the raster map, since you know for sure
what the result is for min, mean, median, max and so on. If this is not
sufficient use r.out.ascii and check against the correct solution that you
have created beforehand. If this is not sufficient then use pygrass and
investigate each raster cell of the resulting output map.

Best regards
Soeren

> Markus M
>
> >
> > Best regards
> > Soeren
> >
> >>
> >> my2c
> >>
> >> Markus M
> >>
> >> >
> >> > Best
> >> > Sören
> >> >
> >> >>
> >> >> One thing we could think about is activating the toolbox idea a bit
> >> >> more
> >> >> and creating a specific OBIA toolbox in addons.
> >> >>
> >> >>> Identified candidates could be added to core once they fulfill the
> >> >>> requirements above. Would that happen only in minor releases or
> would
> >> >>> that also be possible in point releases?
> >> >>
> >> >>
> >> >> Adding modules to core is not an API change, so I don't see why they
> >> >> can't
> >> >> be added at any time. But then again, having a series of new modules
> >> >> can be
> >> >> sufficient to justify a new minor release ;-)
> >> >>
> >> >>> Or is that already too much formality and if someone wishes to see
> an
> >> >>> addon in core that is simply discussed on ML?
> >> >>
> >> >>
> >> >> Generally, I would think that discussion on ML is the best way to
> >> >> handle
> >> >> this.
> >> >>
> >> >> Moritz
> >> >>
> >> >>
> >> >> _______________________________________________
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> >> >> grass-dev at lists.osgeo.org
> >> >> http://lists.osgeo.org/mailman/listinfo/grass-dev
> >> >
> >> > _______________________________________________
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> >
> >
>
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