FindPytest.cmake

# Discover required Pytest target.
#
# This module defines the following imported targets:
#     Pytest::Pytest
#
# It also exposes the 'pytest_discover_tests' function, which adds CTest
# test for each Pytest test. The "BUNDLE_PYTHON_TESTS" environment variable
# can be used to run all discovered tests together.
#
# Usage:
#     find_package(Pytest)
#     find_package(Pytest REQUIRED)
#     find_package(Pytest 4.6.11 REQUIRED)
#
# Note:
#     The Pytest_ROOT environment variable or CMake variable can be used to
#     prepend a custom search path.
#     (https://cmake.org/cmake/help/latest/policy/CMP0074.html)

cmake_minimum_required(VERSION 3.20...4.2)

include(FindPackageHandleStandardArgs)

find_program(PYTEST_EXECUTABLE NAMES pytest)
mark_as_advanced(PYTEST_EXECUTABLE)

if(PYTEST_EXECUTABLE)
    execute_process(
        COMMAND "${PYTEST_EXECUTABLE}" --version
        OUTPUT_VARIABLE _version
        ERROR_VARIABLE _version
        OUTPUT_STRIP_TRAILING_WHITESPACE
    )

    if (_version MATCHES "pytest (version )?([0-9]+\\.[0-9]+\\.[0-9]+)")
        set(PYTEST_VERSION "${CMAKE_MATCH_2}")
    endif()
endif()

find_package_handle_standard_args(
    Pytest
    REQUIRED_VARS
        PYTEST_EXECUTABLE
    VERSION_VAR
        PYTEST_VERSION
    HANDLE_COMPONENTS
    HANDLE_VERSION_RANGE
)

if (Pytest_FOUND AND NOT TARGET Pytest::Pytest)
    add_executable(Pytest::Pytest IMPORTED)
    set_target_properties(Pytest::Pytest
        PROPERTIES
            IMPORTED_LOCATION "${PYTEST_EXECUTABLE}")

    # Function to discover pytest tests and add them to CTest.
    function(pytest_discover_tests NAME)
        set(_BOOL_ARGS
          STRIP_PARAM_BRACKETS
          INCLUDE_FILE_PATH
          BUNDLE_TESTS
        )

        set(_SINGLE_VALUE_ARGS
          WORKING_DIRECTORY
          TRIM_FROM_NAME
          TRIM_FROM_FULL_NAME
        )

        set(_MULTI_VALUE_ARGS
          TEST_PATHS
          LIBRARY_PATH_PREPEND
          PYTHON_PATH_PREPEND
          ENVIRONMENT
          PROPERTIES
          DEPENDS
          EXTRA_ARGS
          DISCOVERY_EXTRA_ARGS
        )

        cmake_parse_arguments(
            PARSE_ARGV 1 ""
            "${_BOOL_ARGS}"
            "${_SINGLE_VALUE_ARGS}"
            "${_MULTI_VALUE_ARGS}"
        )

        # Set platform-specific library path environment variable.
        if (CMAKE_SYSTEM_NAME STREQUAL Windows)
            set(LIBRARY_ENV_NAME PATH)
        elseif(CMAKE_SYSTEM_NAME STREQUAL Darwin)
            set(LIBRARY_ENV_NAME DYLD_LIBRARY_PATH)
        else()
            set(LIBRARY_ENV_NAME LD_LIBRARY_PATH)
        endif()

        # Convert paths to CMake-friendly format.
        if(DEFINED ENV{${LIBRARY_ENV_NAME}})
            cmake_path(CONVERT "$ENV{${LIBRARY_ENV_NAME}}" TO_CMAKE_PATH_LIST LIBRARY_PATH)
        else()
            set(LIBRARY_PATH "")
        endif()
        if(DEFINED ENV{PYTHONPATH})
            cmake_path(CONVERT "$ENV{PYTHONPATH}" TO_CMAKE_PATH_LIST PYTHON_PATH)
        else()
            set(PYTHON_PATH "")
        endif()

        # Prepend specified paths to the library and Python paths.
        if (_LIBRARY_PATH_PREPEND)
            list(REVERSE _LIBRARY_PATH_PREPEND)
            foreach (_path ${_LIBRARY_PATH_PREPEND})
                set(LIBRARY_PATH "${_path}" "${LIBRARY_PATH}")
            endforeach()
        endif()

        if (_PYTHON_PATH_PREPEND)
            list(REVERSE _PYTHON_PATH_PREPEND)
            foreach (_path ${_PYTHON_PATH_PREPEND})
                set(PYTHON_PATH "${_path}" "${PYTHON_PATH}")
            endforeach()
        endif()

        # Set default working directory if none is specified.
        if (NOT _WORKING_DIRECTORY)
            set(_WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
        endif()

        get_filename_component(_WORKING_DIRECTORY "${_WORKING_DIRECTORY}" REALPATH)

        # Override option by environment variable if available.
        if (DEFINED ENV{BUNDLE_PYTHON_TESTS})
            set(_BUNDLE_TESTS $ENV{BUNDLE_PYTHON_TESTS})
        endif()

        # Define file paths for generated CMake include files.
        set(_include_file "${CMAKE_CURRENT_BINARY_DIR}/${NAME}_include.cmake")
        set(_tests_file "${CMAKE_CURRENT_BINARY_DIR}/${NAME}_tests.cmake")

        add_custom_command(
            VERBATIM
            OUTPUT "${_tests_file}"
            DEPENDS ${_DEPENDS}
            COMMAND ${CMAKE_COMMAND}
            -D "PYTEST_EXECUTABLE=${PYTEST_EXECUTABLE}"
            -D "TEST_PATHS=${_TEST_PATHS}"
            -D "TEST_GROUP_NAME=${NAME}"
            -D "BUNDLE_TESTS=${_BUNDLE_TESTS}"
            -D "LIBRARY_ENV_NAME=${LIBRARY_ENV_NAME}"
            -D "LIBRARY_PATH=${LIBRARY_PATH}"
            -D "PYTHON_PATH=${PYTHON_PATH}"
            -D "TRIM_FROM_NAME=${_TRIM_FROM_NAME}"
            -D "TRIM_FROM_FULL_NAME=${_TRIM_FROM_FULL_NAME}"
            -D "STRIP_PARAM_BRACKETS=${_STRIP_PARAM_BRACKETS}"
            -D "INCLUDE_FILE_PATH=${_INCLUDE_FILE_PATH}"
            -D "WORKING_DIRECTORY=${_WORKING_DIRECTORY}"
            -D "ENVIRONMENT=${_ENVIRONMENT}"
            -D "TEST_PROPERTIES=${_PROPERTIES}"
            -D "CTEST_FILE=${_tests_file}"
            -D "EXTRA_ARGS=${_EXTRA_ARGS}"
            -D "DISCOVERY_EXTRA_ARGS=${_DISCOVERY_EXTRA_ARGS}"
            -P "${CMAKE_CURRENT_FUNCTION_LIST_DIR}/PytestAddTests.cmake")

        # Create a custom target to run the tests.
        add_custom_target(${NAME} ALL DEPENDS ${_tests_file})

        file(WRITE "${_include_file}"
            "if(EXISTS \"${_tests_file}\")\n"
            "    include(\"${_tests_file}\")\n"
            "else()\n"
            "    add_test(${NAME}_NOT_BUILT ${NAME}_NOT_BUILT)\n"
            "endif()\n"
        )

        # Register the include file to be processed for tests.
        set_property(DIRECTORY
            APPEND PROPERTY TEST_INCLUDE_FILES "${_include_file}")

    endfunction()

endif()