cmake -S . -B build cmake --build build ctest --test-dir build ================= OUTPUT ============== Test project XXXXX Start 1: saxpy_test 1/3 Test #1: saxpy_test ....................... Passed 0.09 sec Start 2: sgemv_test 2/3 Test #2: sgemv_test ....................... Passed 0.00 sec Start 3: rand_mat_svd_test 3/3 Test #3: rand_mat_svd_test ................ Passed 0.08 sec

Despite its age, Fortran continues to reign as the dominant language in advanced numerical algorithms and physics simulations. Cutting-edge numerical algorithms, including BLAS3-based LU, QR, RRQR, and implementations of eigenvalue/svd with divide-and-conquer, are exclusively found in LAPACK, setting it apart from competing clones like Eigen or Armadillo. This makes Fortran the preferred choice for researchers developing new algorithms, as it provides a foundation for benchmarking against established baselines written in the language.

While Fortran lacks a standardized unit testing framework, developers have devised custom testing systems for their projects. Unfortunately, many Fortran-based unit test frameworks suffer from infrequent updates due to the language's lesser popularity, leading to their exclusion from consideration. In pursuit of solutions with minimal dependencies and robust support in major systems like CMake and CTest, pyohannes introduced a groundbreaking demo utilizing solely CMake and CTest for Fortran (link). We have further enhanced this solution by eliminating the need for platform-dependent symbol mangling and enabling the grouping of multiple unit tests within a single Fortran file.

Users can group multiple tests into a single module as follows. The test functions return 0s on success, otherwise it is treated as failures.

! my_tests.f90 module my_tests_mod use iso_fortran_env use iso_c_binding implicit none contains integer function my_test_success() result(ret) bind(C) ret = 0 end function my_test_success integer function my_test_fail() result(ret) bind(C) ret = 1 end function my_test_fail end module my_tests_mod

Since we used bind(C) in the Fortran code, we don't need the symbol mangling that pyohannes used. Creating a test binary with CMake is quite simple as follows:

project(fortran_test) enable_language(Fortran) set(TEST_LIST my_test_success my_test_fail ) create_test_sourcelist(_ my_tests_main.c ${TEST_LIST}) add_executable(my_tests my_tests_main.c my_tests.f90) foreach (test ${TEST_LIST})  add_test(NAME ${test} COMMAND my_tests ${test}) endforeach ()

1. Begin by specifying the list of Fortran functions to be tested in a variable named TEST_LIST.
2. Use create_test_sourcelist to generate a C file responsible for handling command line parsing, providing logging support, and forward declaring the test functions listed in TEST_LIST.
3. Proceed to create the test executable using add_executable. Ensure to include all necessary source dependencies within this macro. If shared library dependencies are required, incorporate target_link_libraries for linking.
4. Conclude by invoking add_test for each test to be executed.

The following snippet builds and runs the tests.

cmake -S . -B build cmake --build build ctest [--verbose] --test-dir build

To write your code in a clean and consistent style, we recommend to format the code with fprettify.

fprettify -i 2 --strict-indent --enable-decl --disable-indent-mod -l 80 FILE.f90

CMake support a wide range of system packages. For the packages that wasn't included by default, user may leverage the built-in pkg-config support in CMake.

find_package(BLAS REQUIRED) find_package(LAPACK REQUIRED) find_package(PkgConfig REQUIRED) pkg_check_modules(EIGEN REQUIRED IMPORTED_TARGET eigen3) target_link_libraries( lapack_test BLAS::BLAS LAPACK::LAPACK PkgConfig::EIGEN )

User may further integrate with github actions for CI:

# .github/workflows/main.yml name: CMake on: push jobs: build-project: name: Build Project runs-on: ubuntu-latest steps: - name: Checkout uses: actions/checkout@v4.1.1 - name: Dependencies uses: awalsh128/cache-apt-pkgs-action@latest with: packages: gfortran libopenblas-dev liblapack-dev version: 1.0 - name: Configure, build, and test uses: threeal/cmake-action@v1.3.0 with: run-build: true run-test: true

• pyohannes/ctest-fortran-unittest
• Unit testing frameworks in Fortran Wiki
• Testing with CMake and CTest
• CMake and PkgConfig
• cache-apt-pkgs-action
• cmake action