Fortuno – flextensible unit testing framework for Fortran

Fortuno (Fortran Unit Testing Objects) is a flexible & extensible, object-oriented unit testing framework designed for the Fortran programming language. It emphasizes ease of use by minimizing boiler plate code when writing tests, while also prioratizing modularity and extensibility. Fortuno provides the essential building blocks to help developers create customized unit testing solutions.

Fortuno provides:

• serial unit testing,
• parallel unit testing for MPI- and coarray-parallel projects,
• simple unit tests,
• fixtured tests,
• parametrized tests,
• automatic test registration (in combination with the Fypp-preprocessor), and
• integration with the fpm, CMake and Meson build systems.

Documentation can be found on the Fortuno documentation site. Additionally, you may want to explore the examples provided in the example folder.

Quickstart

The easiest way to begin a new project with the Fortuno unit testing framework is by using the Cookiecutter-Fortran-project template generator. This tool creates a minimal project setup that’s ready for building, testing, and installation, with options to select your preferred build system (CMake, Fpm, or Meson), parallelization method (serial, MPI-parallel, or coarray-parallel), and built-in Fortuno integration.

If you'd like to add Fortuno unit tests to an existing project, follow the instructions below. In the examples, it’s assumed your library includes a module called mylib that provides a factorial() function for calculating the factorial of integers. You can adjust these names to match your actual library and function names.

Obtaining Fortuno during your build process

If you project is built with Fpm, CMake or Meson, the simplest way to integrate Fortuno is by downloading and building it as part of your project's build process. The steps vary depending on the build system you're using:

• Fpm: Add Fortuno as a development dependency by including the following lines in your fpm.toml file:

  • Serial interface:

    [dev-dependencies]
    fortuno = { git = "https://github.com/fortuno-repos/fortuno-fpm-serial.git" }
    

  • MPI interface:

    [dev-dependencies]
    fortuno = { git = "https://github.com/fortuno-repos/fortuno-fpm-mpi.git" }
    

  • Coarray interface:

    [dev-dependencies]
    fortuno = { git = "https://github.com/fortuno-repos/fortuno-fpm-coarray.git" }
    

• CMake: Add the relevant snippet to your project's CMakeLists.txt file:

  • Serial interface:

    include(FetchContent)
    FetchContent_Declare(
      Fortuno
      GIT_REPOSITORY "https://github.com/fortuno-repos/fortuno"
      GIT_TAG "main"
    )
    FetchContent_MakeAvailable(Fortuno)
    

  • MPI interface:

    option(FORTUNO_WITH_MPI "Fortuno: whether to build the MPI interface" ON)
    include(FetchContent)
    FetchContent_Declare(
      Fortuno
      GIT_REPOSITORY "https://github.com/fortuno-repos/fortuno"
      GIT_TAG "main"
    )
    FetchContent_MakeAvailable(Fortuno)
    

  • Coarray interface:

    option(FORTUNO_WITH_COARRAY "Fortuno: whether to build the coarray interface" ON)
    include(FetchContent)
    FetchContent_Declare(
      Fortuno
      GIT_REPOSITORY "https://github.com/fortuno-repos/fortuno"
      GIT_TAG "main"
    )
    FetchContent_MakeAvailable(Fortuno)
    

    Additionally, you may want to define the cache variables FORTUNO_FFLAGS_COARRAY and FORTUNO_LDFLAGS_COARRAY with the appropriate compiler and linker flags for coarray parallelism.

    Note: If Fortuno is already installed on your system, the settings described above will automatically use the installed version rather than downloading and building it during your project's build process.

• Meson: Create a fortuno.wrap file in the subprojects/ directory (create it if it doesn’t already exist) with the following content:

  [wrap-git]
  directory=fortuno
  url=https://github.com/fortuno-repos/fortuno
  revision=main
  

  Register Fortuno as a subproject by adding the following to your main meson.build file:

  • Serial interface:

    fortuno_serial_dep = dependency(
      'fortuno_serial',
      fallback: ['fortuno', 'fortuno_serial_dep']
    )
    

  • MPI interface:

    fortuno_mpi_dep = dependency(
      'fortuno_mpi',
      fallback: ['fortuno', 'fortuno_mpi_dep'],
      default_options: {'with_mpi': true}
    )
    

  • Coarray interface:

    fortuno_coarray_dep = dependency(
      'fortuno_coarray',
      fallback: ['fortuno', 'fortuno_coarray_dep'],
      default_options: {
        'with_coarray': true,
        'fflags_coarray': fflags_coarray,
        'ldflags_coarray': ldflags_coarray,
      },
    )
    

    The variables fflags_coarray and ldflags_coarray should be defined in your project to contain the flags required to compile and link coarray-parallel code.

    Note: If Fortuno is already installed on your system, the settings described above will automatically use the installed version rather than downloading and building it during your project's build process.

Installing Fortuno on your system

As an alternative to downloading and building Fortuno on-the-fly during your project's build process, it is also possible to install the library directly on your system and use the installed version during the build. This can be useful for avoiding repeated downloads as well as for using Fortuno with other build systems (e.g. Make).

Installing from source

To install Fortuno from the downloaded source, you must follow the standard CMake workflow:

• Review the config.cmake file for variables that allow you to customize the build.

• Configure Fortuno:

  mkdir build
  FC=gfortran cmake -DCMAKE_INSTALL_PREFIX=${HOME}/opt/fortuno -B build
  

  Ensure CMake selects the correct Fortran compiler by explicitly setting the FC environment variable. You should also customize the installation directory by setting the CMAKE_INSTALL_PREFIX variable accordingly.

• Build the library:

  cmake --build build
  

• Install Fortuno:

  cmake --install build
  

Using the installed library

How you integrate the installed Fortuno library into your project depends on the build system you are using for your project:

• CMake: Follow the CMake instructions outlined earlier. Ensure the CMAKE_PREFIX_PATH environment variable includes Fortuno's installation location so that CMake can find the library. For example:

  export CMAKE_PREFIX_PATH="${HOME}/opt/fortuno:${CMAKE_PREFIX_PATH}"
  

• Meson: Follow the Meson instructions from the previous section. Make sure to set the PKG_CONFIG_PATH environment variable to include Fortuno’s installation location so that Meson can locate the library. For example:

  export PKG_CONFIG_PATH="${HOME}/opt/fortuno/lib/pkgconfig:${PKG_CONFIG_PATH}"
  

  (Depending on your Linux distribution, you might need to use lib64 instead of lib in the path.)

• Other build systems (e.g., Make): Add the directory containing the installed .mod files to the compiler's search path during compilation using the appropriate flag for your compiler, for example:

  -I${HOME}/opt/fortuno/lib/modules
  

  When linking the test application, ensure you link the appropriate interface-specific library and the general library using the correct compiler flags. For example:

  -L${HOME}/opt/fortuno/lib -lfortuno_serial -lfortuno
  

  (You may need to use lib64 instead of lib in the paths, depending on your system's configuration.)

Writing unit tests

In Fortuno, writing unit tests is straightforward. For basic cases, tests are written as simple subroutines without arguments. Aside from the test routines themselves, only a minimal amount of additional code is required to register the tests in the framework and provide a command-line test driver to execute them.

For example, given a hypothetical library mylib that provides a factorial() function, a minimal test program checking the results for two different input values might look like this:

! file: testapp.f90

!> Module containing the tests
module testapp_tests
  use mylib, only : factorial
  use fortuno_serial, only : is_equal, test => serial_case_item, check => serial_check, test_list
  implicit none

contains

  !> Returns the tests in this module
  function tests()
    type(test_list) :: tests

    tests = test_list([&
        test("factorial_0", test_factorial_0),&
        test("factorial_1", test_factorial_1)&
    ])

  end function tests

  ! Test: 0! = 1
  subroutine test_factorial_0()
    call check(factorial(0) == 1)
  end subroutine test_factorial_0

  ! Test: 1! = 1
  ! This routine uses is_equal() for comparison in order to obtain detailed
  ! information in case of a failure.
  subroutine test_factorial_1()
    call check(is_equal(factorial(1), 1))
  end subroutine test_factorial_1

end module testapp_tests


!> Test app driving Fortuno unit tests.
program testapp
  use fortuno_serial, only : execute_serial_cmd_app
  use testapp_tests, only : tests
  implicit none

  ! Register tests by providing name and subroutine to run for each test.
  ! Note: this routine does not return but stops the program with the right exit code.
  call execute_serial_cmd_app(tests())

end program testapp

Bulding the test-driver app

To run your unit tests, you'll first need to build the test driver app using your chosen build system:

• Fpm: If the testapp.f90 source file is stored in the test/ folder, fpm will automatically compile it and link it with the Fortuno library when you build your project. Simply run:

  fpm build
  

• CMake: In your CMakeLists.txt file, declare an executable testapp using testapp.f90 as the source file and add Fortuno::fortuno_serial as a dependency. Be sure to also link your library (e.g. mylib). Additionally, register the executable as a test, so that it can be executed with ctest:

  add_executable(testapp testapp.f90)
  target_link_libraries(testapp PRIVATE mylib Fortuno::fortuno_serial)
  add_test(NAME factorial COMMAND testapp)
  

  Note: If you are using the MPI or coarray interface, replace Fortuno::fortuno_serial with Fortuno::fortuno_mpi or Fortuno::fortuno_coarray, respectively.

  Ensure that you call enable_testing() in your main CMakeLists.txt file before defining the rules for testapp so that ctest can be used for testing.

  Afterward, configure and build your project as usual:

  cmake -B _build
  cmake --build _build
  

• Meson: In the meson.build file, declare an executable testapp using testapp.f90 as the source and fortuno_serial_dep as a dependency. Also include your library (e.g., mylib_dep) as a dependency:

  testapp_exe = executable(
    'testapp',
    sources: ['testapp.f90'],
    dependencies: [mylib_dep, fortuno_serial_dep],
  )
  test('factorial', testapp_exe)
  

  Note: If you're using the MPI or coarray interface, replace fortuno_serial_dep with fortuno_mpi_dep or fortuno_coarray_dep, respectively.

  Build your project as usual:

  meson setup _build
  ninja -C _build
  

Running the tests

Once your test driver app is built, you can run the unit tests using the testing features of your build system:

• Fpm:

  fpm test
  

• CMake:

  ctest --verbose --test-dir _build
  

• Meson:

  meson test -v -C _build
  

The test results are conveyed through the exit code of the test app: zero indicates success, while a non-zero value signals a failure. Additionally, Fortuno logs detailed information to the console during the test run:

=== Fortuno - flextensible unit testing framework for Fortran ===

# Executing test items
..

# Test runs
Total:      2
Succeeded:  2  (100.0%)

=== Succeeded ===

Further information

For more detailed explanations, additional features, and various use cases, refer to the Fortuno documentation and explore the examples in the example folder.

Compiler compatibility

To provide a simple interface along with maximum flexibility and extensibility, Fortuno leverages modern Fortran constructs extensively. Therefore, building Fortuno requires a compiler that supports Fortran 2018. Below is a table of compilers that have been successfully tested for building Fortuno. We recommend using these or newer versions.

Compiler	Status
Intel 2024.{0,1,2}	OK (serial, mpi, coarray)
NAG 7.2 (build 7202)	OK (serial, mpi, coarray)
GNU 13.2, 14.1	OK (serial, mpi) untested (coarray)

If you know of other compilers that can successfully build Fortuno, please consider opening a pull request to update this table.

License

Fortuno is licensed under the BSD-2-Clause Plus Patent License. This OSI-approved license combines the 2-clause BSD license with an explicit patent grant from contributors. The SPDX license identifier for this project is BSD-2-Clause-Patent.