[TIP] mocking a file in /proc

[Gregory Salvan]

Hello,
I've seen no answer concerning TDD, I'll try to give you one.
TDD means fast feedback, so tests must execute fast, and so you're looking
for a design that's testable without reading your data in files.
In the TDD point of view, you'll have a code design where data are raw
injected in the function you're testing and testing if data are well read
is a non sense (for TDD only)
Hope it's clear.





2017-05-09 11:29 GMT+02:00 David Palao <dpalao.python at gmail.com>:

> Hello,
> After playing around with systemfixtures, I don't find a way to make
> it work for my purposes.
> I'm inclined to think that chroot is the answer to my question (thank
> you, Johan, for pointing it out from the beginning).
>
> As I  explained in my first post, I need a way to provide a fake
> filesystem to my functional tests. What I mean by functional tests is
> testing from the point of view of the user. What I do for that is: I
> call the executable from within my FTs, catch the output and compare
> it with the expected output.
> To call the executable I use subprocess.Popen. In principle it should
> be possible to provide a fake fs to it but, isn't it, at the end of
> the day, the same as creating a chroot jail?
>
> Unless there is an easy way to do what I need using systemfixtures (or
> fakefs), which I don't see, I think I will need to go to chroot (or
> docker). Any recommended tool to create a basic chroot jail with
> python in it that I can use to run my program and modify files in
> /proc?
>
> Thanks in advance.
>
> Best
>
> 2017-01-24 15:08 GMT+01:00 Johan Olsen <ulf.johan.olsen at gmail.com>:
> > Hello,
> >
> > I would solve this by running my program in a chroot environment in some
> > way. Chroot is used to change the apparent root directory for some
> running
> > process and its children. You can then set up a mock /proc under e.g.
> > /tmp/mock, and run your tests with chroot under pretense that /tmp/mock
> is
> > your actual root folder. From python you can do this with os.chroot.
> >
> > Regards,
> > Johan Olsén
> >
> >
> >
> > 2017-01-24 14:51 GMT+01:00 David Palao <dpalao.python at gmail.com>:
> >>
> >> Hello,
> >> I am writing a program that does something based on information read
> >> from /proc (the target OS is linux). But I have some problems figuring
> >> out how to mock the /proc filesystem, or at least, some files in it.
> >>
> >> The rationale is that I want to change some files inside /proc to
> >> simulate different configurations of the host computer so that I can
> >> run my functional tests against those different configurations.
> >>
> >> I was thinking in using docker for this task. But
> >> 1) this is offtopic here :)
> >> and
> >> 2) I would like to learn what is the standard way to deal with such
> >> situations. If there is a "standard way" at all... I mean, what am I
> >> supposed to do from the point of view of TDD?
> >>
> >> I would appreciate if someone with experience in such problems could
> >> share some advice.
> >>
> >> Best,
> >>
> >>
> >> David
> >>
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> >
> >
>
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