Cosmology System Test & Gravity Support in `SystemTestRunner` Class

[bcaddy]

Summary

• Added gravity support to the SystemTestRunner class
• Added a cosmology system test. Thank you to @bvillasen for providing the initial conditions and parameter files and helping answer my questions about this test problem.
• Added Dual Energy to the default cosmology build
• Make PPMP default for cosmo builds per offline discussion with @evaneschneider and @bvillasen
• Updated the combine_hydro_particles.py script to work with gravity files as well. Now named combine_test_files.py
• Fixed a few typos

[evaneschneider]

Is this ready to be merged? There is still a conflict with the test data.

[bcaddy]

I fixed the conflict. I'm running into a weird bug with some tests with DE turned on failing. I'll let you know when I have that resolved

[bcaddy]

This is ready to merge.

The bug was due to cosmology using a different value of DE_ETA_1 which changed the pressure in some tests. I've added handling for this to those tests.

[evaneschneider]

Just so I understand, which tests exactly did you need to change? The change by several orders of magnitude in the pressure is surprising to me, but maybe it's because I don't understand what is being compared.

[bcaddy]

tALLLoadCellPrimitive and tALLReconstructionLoadData. DE_ETA_1 is very different in cosmology builds so which leads to the difference.

[evaneschneider]

I'm still not understanding. Don't those tests just load in fidicuial data? So why is the data different? I understand that the eta value is different, but I'm not understanding what the test data represents.

[bcaddy]

Both of the functions being tested call the "get pressure from DE" function which internally depends on the value of DE_ETA_1 and the difference in that is enough with this fiducial data to change how it's handled.

[evaneschneider]

I see, thank you.