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CP2K Regression Testing

CP2K comes with over 3000 test input files (located in tests) which serve as both examples on how to use the many features in CP2K and also as a method for developers to test modifications and extensions to CP2K. In order to reduce the chance of bugs being introduced into the code, and ensure that all parts of the code are working. We also recommend that all users complete a test before using a self-compiled binary for their projects.


A number of regtests are run automatically by various members of our community. The results of these tests are collected centrally at the Dashboard . If errors are detected, the developer responsible for the change should fix it immediately. The output logs provide the arch file used for these tests, which might suggest useful settings for that particular architecture.

Code Coverage

We aim that the regression test suite covers all the functionality of CP2K. For this purpose we regularly create Coverage Reports of the test-suite. If you see parts of the code which are not well tested, please contribute to improving coverage by writing new tests!

How does it work?

The regression test suite is run using the do_regtest script. It performs the following tasks:

  • performs a realclean build of the source
  • executes a list of tests
  • compares the results (outputs) with those of the last known result (reference)
  • produces a summary

Running the regtests

Step 0: make based testing

  • If you are able to build and run cp2k on the local machine the easiest way is to start the regtesting by running make ARCH=… VERSION=… test. The options listed in Step 2 can also be specified with make via TESTOPTS+=<options>, e.g. TESTOPTS+=“-mpiranks 4 -ompthreads 4” requires 4 MPI ranks and 4 OpenMP threads for each MPI rank.
  • Be careful about the value of -j parameter you will use; running too many tests in parallel can cause tests to fail due to lack of system and/or GPU memory.
  • If this fails (e.g. on batch systems), continue with Step 1 else go to interpretation.

Step 1: Preparation

  • Decide on a directory for doing the regtest, there will be plenty of files in this dir (after a while) so make it something like $HOME/rt
  • Clone a version of cp2k into $HOME/rt.
  • Set up the arch files so that you can cleanly build cp2k (test this)

Step 2: Running

$ tools/regtesting/do_regtest --help
Usage: do_regtest [OPTION]
Run the CP2K regression test suite
Example: do_regtest -c my_regtest.conf

  -h, -help, --help         print this help screen.
  -c, -config FILE          read any of the following configuration switches from FILE.
  -cp2kdir PATH             location of cp2k source tree relative to current working directory.
  -dirout PATH              root path of output folder (default: current working directory).
  -mpiexec EXE              name of the executable to run mpi-ranks. Default: mpiexec.

  -version VERSION          VERSION passed to make. Default: sopt.
  -arch ARCH                ARCH passed to make. Default: Linux-x86-64-gfortran.
  -quick                    rebuild if needed, but without realclean. Default: off.
  -nobuild                  do not build cp2k, rely on user's build. Default: off.

  -mpiranks NRANKS          number of mpi-ranks. Default: 2 for parallel versions, 1 for serial.
  -ompthreads NTHREADS      number of OpenMP threads. Default: 2 for smp versions otherwise 1.
  -maxtasks NPROCS          total number of processor to use. Default: `nproc`.
  -maxbuildtasks NPROCS     total number of processor to use for compilation. Default taken from -maxtasks.
  -jobmaxtime SECONDS       maximum execution time of a single test. Default 600.
  -farming                  test via a single farming run (only for parallel cp2k).

  -noreset                  do not reset the reference outputs. Default: off.
  -shard ISHARD NSHARDS     do sharding: Divide the test dirs into NSHARD subsets and only run the ISHARD-th set.
  -skiptest                 do not run test, only build. Default: off.
  -skipunittest             do not run unit tests. Default: off.
  -skipdir TESTDIR          do not run tests in TESTDIR. This switch can repeated.
  -restrictdir TESTDIR      run only tests in TESTDIR. This switch can repeated.
  -retest                   run only tests in directories, which had failing tests in previous run.

Exit codes:
    0   clean exit with testing
    3   problem with realclean
    4   build errors
    5   problem with retest option - no TEST directory with latest test results found
    6   problem with retest option - no error summary exists in the last TEST directory
    7   reference directory is locked
    8   ctrl-C (SIGINT) and various other signals trapped

For more information visit: <>

Step 3: Interpretation

A test results can be any of the following:

Test Result Meaning
OK if the results match those of a previous run precisely. The execution time is also given.
NEW if they have not been executed previously. The reference result is generated automatically in this run. Tests can also be NEW if they have been reset, i.e. been newly added to the TEST_FILES_RESET files.
RUNTIME FAILURE if they stopped unexpectedly (e.g. core dump, or stop)
WRONG RESULT if they produce a result that deviates (even a tiny bit) from an old reference

The last two outcomes generally mean that a bug has been introduced, which requires investigation. Since regtesting only yields information relative to a previously known result, it is most useful to do a regtest before and after you make changes. To allow per-test numerical difference higher than that set as a default, add third column in appropriate TEST_FILES file with a relative value of the difference.

Adding and Resetting Tests

The test-suite is fully controlled by the following files in the tests directories

File Name Content
TEST_DIRS is just a list of directories that contain tests. You can add your directory here.
TEST_FILES the list of input files that need to be executed. You can add your file name here. Adding a comment about what it tests might help later debugging problems if a regtest fails
TEST_FILES_RESET you can add files for which the reference output became invalid (e.g. bug fix) to this list of files. However be absolutely sure that the change is due to a bug fix, do not reset these that fail because of unclear reasons. Try to add a comment to the git message and/or the file itself
TEST_TYPES this file allows you to create a new test type. I.e. to specify for which words should be grepped and what field should be used in the numerical comparison.
dev/regtesting.txt · Last modified: 2020/08/21 10:15 (external edit)