[lldb-dev] unit testing C++ code in LLDB

[Zachary Turner]

I think it diminishes their usefulness if they're only available to people
willing to run them a specific way.  The python support on Windows isn't as
rosy as it is on other platforms, and it's still very difficult to build
LLDB with python support on Windows.  I might be the only person doing it.
I'm trying to improve it, but I don't see it being in the same place as it
is on other platforms for a while.

Even ignoring that though, I think if your test needs to do setup in
python, it should just be a regular python test of the public API like
everything else.  Regardless, the functionality available to you from C++
is a superset of that available to you from python.  You can even use the
actual public API from C++, which is the same as what you'd be doing in
python.  If you actually need to piggyback off of lots of already-written
python code, then I'm wondering why this particular test is better suited
for a gtest.  Why not just make it a python test?

On Fri, Oct 3, 2014 at 11:01 AM, Sean Callanan <scallanan at apple.com> wrote:

> Zach,
>
> I can live with two entry points – one without the Python dependency, one
> accessible through Python.  As you (and Greg, in the past) suggest, we can
> have a special public API for running unit tests – probably only in debug
> builds – and use that API from Python.
>
> I’m not sure that all internal unit tests should do their setup in C++.  I
> think it makes the test more fragile – and wastes a lot of the machinery we
> already have – to write a bunch of process-control logic in C++ when what I
> actually want to test is something specific in an unrelated class.  LLDB is
> pretty closely tied to Python – for the test cases I write for the
> expression parser, I think I’d be willing to mandate that Python be
> available rather than make setup more challenging.
>
> So that both use cases can coexist, we can just make sure that both the
> gtest runner and the SB API have the ability to run a subset of the unit
> tests; the gtest runner runs all those that don’t require external setup,
> and the SB API can select the tests that need to run with a specific
> initial setup.
>
> Is that something that gtest would support?
>
> Sean
>
> On Oct 3, 2014, at 10:37 AM, Zachary Turner <zturner at google.com> wrote:
>
> I don't think the unit tests should depend on the python tests.  They
> should be self contained.  In other words, the unit tests must be useful to
> someone who is compiling without support for embedded python.  I wouldn't
> want to have a unit test which is only useful if it's called from Python
> which has already done some initial setup.  Still, if you want to avoid
> having another entry poitn for convenience, you could expose something from
> the public API that allows you to just say "run all the unittests".  But
> there shouldn't be any setup in the python.  All the setup necessary to run
> a given test should happen in C++.
>
> On Fri, Oct 3, 2014 at 10:23 AM, Sean Callanan <scallanan at apple.com>
> wrote:
>
>>
>> > On Oct 2, 2014, at 9:27 PM, Todd Fiala <tfiala at google.com> wrote:
>> >
>> > Hey Sean!
>> > …
>>
>> Thanks for the introduction!  It looks like this is definitely in the
>> direction of what I want.
>>
>> > If we want to do collaboration tests (integration tests, etc.), we're
>> probably into the "should be in python category", but we might have a few
>> low-level multi-class testing scenarios where we might want a different
>> gtest/functional, gtest/integration or something similar directory
>> structure to handle those.  Would be good to have discussion around that if
>> we find a valid use for it.
>>
>> One thing I would like to be able to do for the expression parser is unit
>> test in the context of a stopped process.
>> I’m thinking of scenarios where I’d like to test e.g. the Materializer’s
>> ability to read in variable data and make correct ValueObjects.
>>
>> One way to achieve this that comes to mind is to have a hook into the
>> unit tests from the Python test suite, so we can set up the program’s state
>> appropriately using our normal Python apparatus and then exercise exactly
>> the functionality we want.
>>
>> Once we’ve got that kind of hook, we could just run all unit tests right
>> from the Python test suite and avoid having another entry point.
>>
>> If you want IDE-friendly output, you could have an IDE-level target that
>> runs test/dotest.py but singles out the unit tests.
>>
>> What do you think?
>>
>> Sean
>>
>
>
>
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