unit_tests
gpu_unit_tests if MFEM is compiled with CUDA/HIP support
sedov_tests_cpu, sedov_tests_debug (and sedov_tests_gpu and sedov_tests_gpu_uvm if GPU is enabled), testing a Sedov hydrodynamics case
tmop_pa_tests_cpu, tmop_pa_tests_debug (and tmop_pa_tests_gpu if GPU is enabled), testing TMOP with partial assembly

There are also parallel versions of these executables (prefixed with p), which are built if MFEM is compiled with MPI enabled.

Basics of using Catch

To run the unit tests, any of the executables listed above can be run from the command line, for example

./unit_tests

which will run all serial unit tests. If you want to run only a specific test case, it is possible to specify the name of the test case as an argument to the test executable (the names of the test cases are given as the first argument to the TEST_CASE macro in the source code). For example

./unit_tests "NCMesh PA diagonal"

will run only test case testing partial assembly of the diagonal on non-conforming meshes. Test cases are optionally given one or more tags, which can be used to group test cases together. Tags can also be specified on the command line, for example

./unit_tests "[NCMesh]"

will run all the tests that relate to non-conforming meshes.

Listing tests and tags

It is possible to list all test cases with the -l flag, for example

./unit_tests -l

will list all serial unit tests, and

./unit_tests -l "[NCMesh]"

will list all test cases with the given tag.

./unit_tests -t

will list all available tags, along with the number of test cases that are assigned to each tag.

Special tags

For the most part, tags are just used to group similar tests together according to their subject matter. However, several specific tags have special meanings, and those are:

[Parallel], which indicates that a test will not be tested with the serial test executables, and will only be tested with the parallel executable (e.g. punit_tests). punit_tests will only run tests marked with [Parallel].
[GPU], which indicates that a test will be tested with the GPU executables (e.g. gpu_unit_tests). These tests will still be run by the standard (CPU) executables. gpu_unit_tests will only run tests marked with [GPU], and its parallel version pgpu_unit_tests will only run tests marked with both [GPU] and [Parallel].
[MFEMData], which indicates that a test requires access to a clone of the MFEM data repository (see the --data flag below), in order to run tests on some larger mesh files. By default, tests tagged with this tag are skipped, unless the --data flag is provided.

Special command line arguments

In addition to the standard Catch command line arguments (which can be viewed with the -h or --help flag), MFEM's unit tests support two additional command line arguments:

--all, which enables some more thorough tests, at the expense of longer runtimes. This sets the global variable launch_all_non_regression_tests to true.
--data, which specifies a path to a clone of the MFEM data repository, which contains some larger mesh files. If this argument is provided, tests tagged with [MFEMData] will be run, and they will have access to the files in the data repo through the mfem_data_dir global variable.

Test output and debug messages

By default, MFEM's unit tests display relatively little output (a couple of info lines at the beginning, and a summary at the end with the number of test cases and assertions that were run). If a test fails, some additional information about the failing test will be printed. Output to mfem::out and mfem::err is suppressed by default.

To enable more verbose test output, run the unit tests with the -s or --success flag, which will print a message for every successful test assertion, including some additional informational messages. With this option, output to mfem::out and mfem::err is enabled.

Writing unit tests

The following are some guidelines for developers writing unit tests:

Give your test case a concise yet descriptive name. Whitespace is allowed.
Tag your test with the relevant tags. Look at similar tags to see what relevant tags are in use. Class names are often used as tags. Another common tag is [PartialAssembly]. See also the section on special tags.
Do not use std::cout or std::cerr in your test. Prefer the Catch macros INFO, CAPTURE, and similar. If you need more control over the output, prefer mfem::out and mfem::err.
Use the GENERATE macro instead of nested for-loops when testing many combinations of parameters.