test: add leaf biophysics pFUnit unit test suite

[johnpaulalex]

(not planning to submit yet, just want to start a discussion)

Add unit tests for LeafBiophysicsMod covering:

• QSat: saturation vapor pressure and specific humidity
• StomatalCondMedlyn and StomatalCondBallBerry: stomatal conductance
• LowstorageMainRespReduction: low-storage maintenance respiration scaling
• LeafLayerMaintenanceRespiration_Ryan_1991 and _Atkin_etal_2017: temperature-dependent respiration
• GetCanopyGasParameters: Michaelis-Menten CO2/O2 temperature scaling

Integrate the new suite into CMakeLists.txt and testing/config/unit.cfg so it is picked up by run_unit_tests.py.

Description:

Collaborators:

Expectation of Answer Changes:

Description of generative AI usage (as necessary)

Checklist

If this is your first time contributing, please read the CONTRIBUTING document.

All checklist items must be checked to enable merging this pull request:

Contributor

• The in-code documentation has been updated with descriptive comments
• The documentation has been assessed to determine if updates are necessary
• Describe use of generative AI (if necessary)

Integrator

• FATES PASS/FAIL regression tests were run
• Evaluation of test results for answer changes was performed and results provided
• FATES-CLM6 Code Freeze: satellite phenology regression tests are b4b

If satellite phenology regressions are not b4b, please hold merge and notify the FATES development team.

Documentation

• Technical Note update:
• User's Guide update:

Test Results:

CTSM (or) E3SM (specify which) test hash-tag:

CTSM (or) E3SM (specify which) baseline hash-tag:

FATES baseline hash-tag:

Test Output:

[rgknox]

Thanks for the submissions @johnpaulalex
Tests are always welcome and certainly useful

[rgknox]

We actually need to start migrating to using this constant in more of the models internal code.