To create a new test case, first make a folder in psi4/tests. The directory name may not contain an underscore; to indicate spaces, use a hyphen instead. This directory will need two files. The first is CMakeLists.txt, which is necessary to add the test case to the suite. This file should have the following lines:

 1 2 3 include(TestingMacros) add_regression_test(directory_name "psi;semicolon_separated-list-of-applicable-test-labels") 

The labels specify which groups of tests include the test case. The psi label should always be added, but the other labels are test-specific. The method tested should always be included, and this is often sufficient. If adding a test for an already existing module, the labels for other tests of the module will suggest other labels to add.

A test requiring over 15 minutes should be labeled longtests. A short test used for general bug checking should be labeled quicktests. A test that confirms PSI4 is operational should be labeled smoketests.

The other necessary file is the input file itself, input.dat. The input file should be just a simple input file to run the test, with small modifications.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 #! RI-SCF cc-pVTZ energy of water, with Z-matrix input and cc-pVTZ-RI auxilliary basis. #! Also a bit more to force a second line. nucenergy = 8.801466202085710 #TEST refenergy = -76.05098402733282 #TEST molecule h2o { symmetry c1 O H 1 1.0 H 1 1.0 2 104.5 } set { basis cc-pVTZ scf_type df df_basis_scf cc-pVTZ-RI e_convergence 10 } thisenergy = energy('rhf') compare_values(nucenergy, h2o.nuclear_repulsion_energy(), 9, "Nuclear repulsion energy") #TEST compare_values(refenergy, thisenergy, 9, "Reference energy") #TEST compare_values(refenergy, get_variable('scf total energy'), 9, "Reference energy") #TEST 

Of those small modifications, first, note the special comment at the top (starting with the #! comment marker). This should be very descriptive since it is inlined into the manual (unless !nosample is present in this comment) as a sample input.

The reference values are assigned to variables for later use. The compare_values function (along with several relatives in psi4/psi4/driver/p4util/util.py for comparing strings, matrices, etc.) checks that the computed values match these reference values to suitable precision. This function prints an error message and signals that the test failed to the make system, if the values don’t match. Any lines of the input associated with the validation process should be flagged with #TEST at the end of each line, so that they can be removed when copying from the tests to the samples directory.

Finally, add the directory name to the list of tests in psi4/tests/CMakeLists.txt.

In preparing the test case, turn energy, density, amplitude, and geometry convergence criteria to very tight levels, and use these results for reference energies, reference geometries, reference cube files, etc.. Then, either remove or relax the convergence settings, if these are not a vital part of the test. In choosing the number of digits for compare_values and other compare_* functions, select a number looser than the convergence set in the test or the default convergence for the calculation type (energy, gradient, etc.).

Sometimes you want to add tests that check several variations of a template job or that test error handling or that are PsiAPI rather than PSIthon focused. In these cases, you’ll want to add to the second test suite that lives at psi4/tests/pytests. Presently, the “normal” (everything in the tests/ directory that isn’t in tests/pytests/) are run through CTest, while the pytests are run through Pytest. In future, all will be run through Pytest, but the former will still be run as PSIthon (psi4 input.dat) while the latter will still be run as PsiAPI (import psi4). In other words, in designing a test, choose its mode based on whether PSIthon or PsiAPI suits it better and whether it’s a simple model for users (probably PSIthon) or for expert users (probably PsiAPI). Both will continue to work in future.
In developing a pytest test, you probably want to edit it in place, rather than running make after each change. Easiest is from <objdir>, run pytest ../tests/pytests. Add any filters (-k test_name_fragment) or parallelism (-n <N> if pytest-xdist installed) or print test names (-v) or print warnings (-rws). To see stdout output from an otherwise passing test, easiest to add assert 0 at its end to trigger failure. An important point is that because they’re PsiAPI, import psi4 is happening, so the <objdir> PSI4 module must be in PYTHONPATH. Also, any call to QCEngine is using which psi4, so the <objdir> PSI4 executable must be in PATH. Easiest thing is to execute <objdir>/stage/bin/psi4 --psiapi and execute what it prints.
• Test file name must start with test_. This is how pytest knows to collect it.
• Test file may contain many tests. To be recognized as a test, the Python function must start with test_.
• No registration required to bring test to pytest’s attention. But to get it installed and runnable by the user through make pytest or tested in the conda build, add it around https://github.com/psi4/psi4/blob/master/psi4/CMakeLists.txt#L245
There are individual “marks” that can be added to whole tests or parts of parameterized tests so that they can be run by category (pytest -m <mark> vs. ctest -L <mark>) rather than just by name (pytest -k <name_fragment> vs. ctest -R <name_fragment>). Most important are “quick” and “long” that opt tests into the quick CI suite or out of the normal full suite. Mark with a decorator for the full test or the marks argument in a parameterized test. Search “mark” in the test suite for examples. Use “quick” freely for tests that cover functionality and are under 15s. Use “long” sparingly to winnow out the longest examples, particularly those over a minute.