[Scons-dev] Unit testing with mock?

[Gary Oberbrunner]

Python mocks are extremely useful. We use them in my day job and
unit-testing that code would be pretty hard without them. The main
counterargument to using them in SCons is that it introduces a dependency,
and to date SCons can build and test with no external dependencies. But of
course that's not _really_ true: many SCons tests test compilers and tools
that are often not present, so those tests get skipped.That's one route you
could take: if no mock module exists, skip the tests. But another way this
has been done in SCons in the past is to copy the module into SCons, e.g.
in the src/engine/SCons/compat subdir, with appropriate name changes. If
the module in question's license permits this, and it's self-contained, why
not do this? In this case it'd probably want to be under QMTest but the
principle is the same.

Quoting from src/engine/SCons/compat/__init__.py:

*This subpackage holds modules that provide backwards-compatible*
*implementations of various things that we'd like to use in SCons but which*
*only show up in later versions of Python than the early, old version(s)*
*we still support.*


Other devs, what do you think?

On Fri, Oct 23, 2015 at 12:27 PM, Paweł Tomulik <ptomulik at meil.pw.edu.pl>
wrote:

> This is the module I'm currently working on:
>
> https://github.com/ptomulik/scons-arguments
>
> for the moment 'devel' branch is more recent:
>
> https://github.com/ptomulik/scons-arguments/tree/devel
>
> Mocks are used in unit tests:
>
>
> https://github.com/ptomulik/scons-arguments/blob/master/unit_tests/SConsArgumentsTests.py
>
> It's hard to tell what's the particular purpose of using mocks for a
> particular project. It's rather a choice of testing philosophy. Mocks
> always play same role: to isolate the behaviour of the object (or
> method) being tested on other objects (or methods). That way less tests
> get affected when a particular object changes its behaviour.
>
>
> W dniu 23.10.2015 o 16:19, Bill Deegan pisze:
> > Pawel,
> >
> > If the plan was to migrate SCons to 3.x and drop support for 2.7, then
> > maybe using mocks would be ok now.
> > But the plan is to support both for some time once we get SCons working
> > with 3.x.
> >
> > What are you using mocks for now? Can you point to a repo?
> > Note that thus far, the mocks module has not been used, so chances are
> > it can be done without additional modules (though perhaps with more
> code).
> >
> > -Bill
> >
> > On Fri, Oct 23, 2015 at 1:56 AM, Paweł Tomulik <ptomulik at meil.pw.edu.pl
> > <mailto:ptomulik at meil.pw.edu.pl>> wrote:
> >
> >     So, what should I replace my existing mocks with? Do you know any
> >     technique?
> >
> >     These mocks would only be required for unit-testing scons package, so
> >     this doesn't affect plain users (only developers and scons package
> >     maintainers would be affected). And starting from 3.3, the mock
> module
> >     is part of python standard.
> >
> >
> >
> >     W dniu 23.10.2015 o 09:21, Alexandre Feblot pisze:
> >     > Hi,
> >     > Please, please, please,
> >     > Don't!
> >     > Don't force people to install additional modules.
> >     > One of Python benefits is how rich its standard distribution is,
> >     compared to perl for example, allowing to distribute code that you
> >     know will work everywhere without additional requirement.
> >     > Please don't break that.
> >     >
> >     > Alexandre
> >     >
> >     >> Le 22 oct. 2015 à 23:58, Pawel Tomulik <ptomulik at meil.pw.edu.pl
> >     <mailto:ptomulik at meil.pw.edu.pl>> a écrit :
> >     >>
> >     >> Hi,
> >     >>
> >     >> If I would like to contribute a module to scons, would it be
> >     acceptable
> >     >> to use mocks (https://pypi.python.org/pypi/mock) in unit tests?
> From
> >     >> what I see, none of the existsing unit tests in SCons use mocks,
> >     perhaps
> >     >> for a reason? Is it forbidden? Is there an alternative without
> >     using the
> >     >> module?
> >     >>
> >     >> The mock module is not included in the basic python distribution,
> >     it has
> >     >> to be installed, for example with pip (it's a backport of
> >     unittest.mock
> >     >> available in python >=3.3).
> >     >>
> >     >>
> >     >> Best regards!
> >     >>
> >     >> --
> >     >> Paweł Tomulik
> >     >>
> >     >> _______________________________________________
> >     >> Scons-dev mailing list
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> >     >
> >
> >
> >     --
> >     Paweł Tomulik, tel. (22) 234 7925
> >     Instytut Techniki Lotniczej i Mechaniki Stosowanej
> >     Politechnika Warszawska
> >     _______________________________________________
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> >
> >
> >
> >
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> >
>
>
> --
> Pawel Tomulik
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>



-- 
Gary
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