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

[Todd Fiala]

> Is that something that gtest would support?

I think gtest is engineered to support having the test runner piece kick
off in multiple scenarios.  I'm using it right now in the mode where gtest
itself provides the "main" and kicks off all the test runs, but I suspect
we can get our hands dirty and specify which test cases to run and control
the run loop for it.  If that's true (which just takes some digging or just
more knowledge of gtest than my standard C++-only
use-the-gtest-provided-main-loop approach has required), seems like
something we could get going.

I am in favor of allowing both those modes fwiw if we're doing more
collaboration-style tests as is indicated by the "let python set it up."
 For straight unit tests, I'd not want to do that if the setup isn't
complicated (canonical example: testing a single class in isolation), but
for configuration of a set of classes the way the lldb is going to be using
them, definitely so.  It's too easy to misconfigure or get false positives
on tests passing when state is configured, and also makes it more brittle
to adjust those setups when we really change the way something is
configured in lldb-proper.

-Todd

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
>>
>
>
>


-- 
Todd Fiala | Software Engineer | tfiala at google.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20141003/20400a5a/attachment.html>