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

[Zachary Turner]

I gave it a brief look, but I didn't get it working.  Clang and LLD both
already do this, so I figured it would be as simple as copying their CMake
for the gtest stuff and fixing it up with LLDB paths.  Unfortunately, I was
getting tons of linker errors, and I'm not really sure why, as there didn't
appear to be much magic there.  I didn't investigate it further after that,
but it would definitely be a good thing to tackle.

On Thu, Oct 2, 2014 at 2:01 PM, Sean Callanan <scallanan at apple.com> wrote:

> At risk of being burnt at the stake for practicing the the necromantic
> arts:
> Jim’s point that internal APIs are somewhat fragile is well taken, and I
> don’t think there’s much value in using internal tests as “more convenient”
> substitutes for external tests.
>
> That said, I think internal unit tests add several benefits that improve
> code:
>
>
>    - *Modular design*.  If clients of an internal object have to do a lot
>    of extra work to make the object work properly, this may indicate a design
>    issue.
>    - *State encapsulation*.  If an object changes behaviors depending on
>    outside state, then that makes it much harder to use.
>    - *Code readability*.  Test cases can demonstrate how an object is
>    intended to be used, and act as compelling witnesses that that use case
>    works.
>
>
> I would be interested in using the expression parser as a guinea pig to
> introduce test-driven methods.
> Todd/Zach, did you ever get a gtest-based unit test system working?
>
> Sean
>
> On Jul 18, 2014, at 6:14 PM, Zachary Turner <zturner at google.com> wrote:
>
> FWIW I'm kind of in favor of bringing in gtest with limited use.  When I
> first started digging into LLDB, probably the first 3-4 bugs I fixed were
> all in IRMemoryMap, and they would all have been caught if the class were
> unit tested properly.
>
>
> On Fri, Jul 18, 2014 at 4:03 PM, Greg Clayton <gclayton at apple.com> wrote:
>
>> We could expose a new static function in SBDebugger:
>>
>> class SBDebugger {
>>
>> static void
>> UnitTest (const char *args);
>>
>> };
>>
>> Then internally it can parse any arguments and run tests as needed? Each
>> class that wants to register unit tests with the debugger during
>> SBDebugger::Initialize() which must be called prior to doing anything with
>> the LLDB API:
>>
>>
>> SBDebugger::Initialize()
>> {
>>     Debugger::Intialize();
>> }
>>
>> Debugger::Initialize()
>> {
>>         ....
>>         NamedPipe:: Initialize();
>> }
>>
>>
>> Then in the static NamedPipe::Initiazize() you could register your unit
>> tests:
>>
>> void
>> NamedPipe::Initialiaze()
>> {
>>     Debugger::RegisterUnitTest(NamedPipe::InitTest1,
>> "NamedPipe::InitTest1"));
>> }
>>
>>
>> Then you could just run:
>>
>> SBDebugger::Initialize();
>> SBDebugger::UnitTest(NULL); // Run all tests
>>
>> Or run individual ones:
>>
>> SBDebugger::Initialize();
>> SBDebugger::UnitTest("--test NamedPipe::InitTest1"); // Run just
>> "NamedPipe::InitTest1"
>>
>> Of course then the LLDB test suite could run these unit tests first to
>> make sure everything is good.
>>
>>
>>
>> > On Jul 16, 2014, at 3:59 PM, Zachary Turner <zturner at google.com> wrote:
>> >
>> > If it makes you feel any better LLVM is leery of it too, and it's only
>> used, as you said, in specialized circumstances.  It's especially useful
>> for testing abstract data types, where you just want to test the interface
>> to a self-contained, reusable class.
>> >
>> >
>> > On Wed, Jul 16, 2014 at 2:25 PM, <jingham at apple.com> wrote:
>> > I'm a little leery about this.  We don't test at the lldb_private layer
>> because those tests are likely to be fragile and easily broken.  For
>> utility classes like NamedPipe I guess I don't so much mind, but I'm not
>> sure its a great idea to do this more generally.
>> >
>> > Jim
>> >
>> > > On Jul 16, 2014, at 9:40 AM, Todd Fiala <tfiala at google.com> wrote:
>> > >
>> > > Hey guys,
>> > >
>> > > Sometimes I have smaller bits of code I'd like to test in LLDB as I'm
>> developing them (i.e. TDD-style) that are C++ and won't be exposed directly
>> via Python.  I'm not sure I've seen any facilities in the LLDB tests for
>> adding such tests.  Essentially I'd want to do something like a gtest or
>> cppunit test.
>> > >
>> > > Do we have any mechanism for doing that currently?  If we do, what is
>> it?  If we don't, how about adding some mechanism to do it after we figure
>> out how we'd like to approach it?  Or, if you have thoughts on a good,
>> simple way to do it from Python that doesn't require extra Python bindings
>> just to do it, that'd be fine by me as well.
>> > >
>> > > If we want to take a concrete example, here is one: I'm adding a
>> NamedPipe class under the host dir.  I'd like to make some simple tests for
>> it, and test it under Linux, Windows and MacOSX.  In the case of Windows,
>> it would be the only real way for me to test that it's behaving exactly as
>> I want at this point.  This isn't the only time I've wanted C++-level tests
>> at a fairly fine granularity, but it's a good example of it.
>> > >
>> > > Any thoughts?
>> > > --
>> > > Todd Fiala |   Software Engineer |     tfiala at google.com |
>> 650-943-3180
>> > >
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