[llvm-dev] [CMake] External File Dependencies for Unit Tests

[Pavel Labath via llvm-dev]

On 25/06/2019 11:24, James Henderson via llvm-dev wrote:
> Hi Alex,
> 
>     Would you recommend that I do what is done in
>     unittest/ObjectYAML/MinidumpYAMLTest.cpp which just uses a string
>     inside the source file, or use an Inputs directory? Both are not
>     great, as you point out about using an Inputs directory
> 
> 
> I'd be inclined to go with the string in the source file approach. It 
> keeps the whole test localised to one place, making it easier to 
> understand what the test is actually testing.
> 
>     Also, I'm not sure that I can create an object without invoking
>     yaml2obj itself, I can't seem to find a function to do this exposed
>     by libObjectYAML.
> 
> 
> It looks to me like you'd need to move big chunks of code out of the 
> yaml2obj tool into the ObjectYAML library. The Minidump version was 
> added quite recently, and took the approach of doing all the layout in 
> the library, whereas for most other formats, the work is done in the 
> executable layer. I think it would be perfectly reasonable to do this 
> code moving, and would then allow you to use the library in your test 
> setup, similar to how minidump works.

[Disclaimer: I'm the person who added the minidump code.]

I would very much like to see this happen. Lldb has some unit tests 
which need to binary files to operate. The way that's handled right now 
is by shelling out to yaml2obj from inside the unit test (so, not from 
cmake). However, it would be infinitely better if we could just invoke a 
library function to do this conversion for us.


> 
>     If I do need to invoke yaml2obj, would you happen to know how to
>     tell CMake to build yaml2obj first, and also where would I find that
>     executable?
> 
> 
> I'm not a CMake expert by any means, but I think you would need to 
> create a dependency on yaml2obj from the test target, then add a step in 
> the test's CMakeLists.txt to run yaml2obj and generate your inputs. I'm 
> still not convinced that it's the right way to go though.

Running yaml2obj from the unit test like lldb does is probably a bit 
better than doing it from cmake. You can search for ReadYAMLObjectFile 
to see how it's done there. However, I wouldn't really recommend 
emulating that... :)

cheers,
pl