Testing in Cholla

Testing in Cholla

This week I started integrating testing into Cholla. The first part of that was just meeting with Evan and discussing general strategy, convetions we should use, etc. The questions and answers from that meeting can be found here in the “Cholla Planning” section. First we need to reorganize Cholla source files a bit so that they all have an appropriate directory, that’s about half done. I started working on puzzling out the build system and how to integrate a testing build into it but all the experts were busy this week so I put that off for now and started working on getting tests to run. I was able to get a simple integration test for the HLLC solver in Cholla running (on GPU and everything) with a custom build script and it works quite well. There were some issues to hammer out, mostly due to my lack of experience with CUDA, but nothing that was too terrible. Unit tests will be challenging in Cholla. Most of the code is fairly large, monolithic, functions and so pretty much all tests are going to end up being integration tests until such time as a refactor can be done. Hopefully between the system and integration tests though we can determine where bugs are with reasonable accuracy.

Code Coverage

It turns out that nvcc and hipcc don’t support code coverage for GPU code at this time. There are some potential workarounds. VectorCAST supports it but that’s an expensive suite of tools intended for embedded devices and probably isn’t useful to us. We also might be able to capture coverage information by using the HIP CPU Runtime and compiling with GCC’s --coverage flag. This may or may not work, I haven’t tested it yet.