CMake/Modules/GoogleTest.cmake

# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

#[=======================================================================[.rst:
GoogleTest
----------

.. versionadded:: 3.9

This module defines functions to help use the Google Test infrastructure.  Two
mechanisms for adding tests are provided. :command:`gtest_add_tests` has been
around for some time, originally via ``find_package(GTest)``.
:command:`gtest_discover_tests` was introduced in CMake 3.10.

The (older) :command:`gtest_add_tests` scans source files to identify tests.
This is usually effective, with some caveats, including in cross-compiling
environments, and makes setting additional properties on tests more convenient.
However, its handling of parameterized tests is less comprehensive, and it
requires re-running CMake to detect changes to the list of tests.

The (newer) :command:`gtest_discover_tests` discovers tests by asking the
compiled test executable to enumerate its tests.  This is more robust and
provides better handling of parameterized tests, and does not require CMake
to be re-run when tests change.  However, it may not work in a cross-compiling
environment, and setting test properties is less convenient.

More details can be found in the documentation of the respective functions.

Both commands are intended to replace use of :command:`add_test` to register
tests, and will create a separate CTest test for each Google Test test case.
Note that this is in some cases less efficient, as common set-up and tear-down
logic cannot be shared by multiple test cases executing in the same instance.
However, it provides more fine-grained pass/fail information to CTest, which is
usually considered as more beneficial.  By default, the CTest test name is the
same as the Google Test name (i.e. ``suite.testcase``); see also
``TEST_PREFIX`` and ``TEST_SUFFIX``.

.. command:: gtest_add_tests

  Automatically add tests with CTest by scanning source code for Google Test
  macros::

    gtest_add_tests(TARGET target
                    [SOURCES src1...]
                    [EXTRA_ARGS args...]
                    [WORKING_DIRECTORY dir]
                    [TEST_PREFIX prefix]
                    [TEST_SUFFIX suffix]
                    [SKIP_DEPENDENCY]
                    [TEST_LIST outVar]
    )

  ``gtest_add_tests`` attempts to identify tests by scanning source files.
  Although this is generally effective, it uses only a basic regular expression
  match, which can be defeated by atypical test declarations, and is unable to
  fully "split" parameterized tests.  Additionally, it requires that CMake be
  re-run to discover any newly added, removed or renamed tests (by default,
  this means that CMake is re-run when any test source file is changed, but see
  ``SKIP_DEPENDENCY``).  However, it has the advantage of declaring tests at
  CMake time, which somewhat simplifies setting additional properties on tests,
  and always works in a cross-compiling environment.

  The options are:

  ``TARGET target``
    Specifies the Google Test executable, which must be a known CMake
    executable target.  CMake will substitute the location of the built
    executable when running the test.

  ``SOURCES src1...``
    When provided, only the listed files will be scanned for test cases.  If
    this option is not given, the :prop_tgt:`SOURCES` property of the
    specified ``target`` will be used to obtain the list of sources.

  ``EXTRA_ARGS args...``
    Any extra arguments to pass on the command line to each test case.

    .. versionchanged:: 3.31
      Empty values in ``args...`` are preserved, see :policy:`CMP0178`.

  ``WORKING_DIRECTORY dir``
    Specifies the directory in which to run the discovered test cases.  If this
    option is not provided, the current binary directory is used.

  ``TEST_PREFIX prefix``
    Specifies a ``prefix`` to be prepended to the name of each discovered test
    case.  This can be useful when the same source files are being used in
    multiple calls to ``gtest_add_test()`` but with different ``EXTRA_ARGS``.

  ``TEST_SUFFIX suffix``
    Similar to ``TEST_PREFIX`` except the ``suffix`` is appended to the name of
    every discovered test case.  Both ``TEST_PREFIX`` and ``TEST_SUFFIX`` may
    be specified.

  ``SKIP_DEPENDENCY``
    Normally, the function creates a dependency which will cause CMake to be
    re-run if any of the sources being scanned are changed.  This is to ensure
    that the list of discovered tests is updated.  If this behavior is not
    desired (as may be the case while actually writing the test cases), this
    option can be used to prevent the dependency from being added.

  ``TEST_LIST outVar``
    The variable named by ``outVar`` will be populated in the calling scope
    with the list of discovered test cases.  This allows the caller to do
    things like manipulate test properties of the discovered tests.

  .. versionchanged:: 3.31
    Empty values in the :prop_tgt:`TEST_LAUNCHER` and
    :prop_tgt:`CROSSCOMPILING_EMULATOR` target properties are preserved,
    see policy :policy:`CMP0178`.

  Usage example:

  .. code-block:: cmake

    include(GoogleTest)
    add_executable(FooTest FooUnitTest.cxx)
    gtest_add_tests(TARGET      FooTest
                    TEST_SUFFIX .noArgs
                    TEST_LIST   noArgsTests
    )
    gtest_add_tests(TARGET      FooTest
                    EXTRA_ARGS  --someArg someValue
                    TEST_SUFFIX .withArgs
                    TEST_LIST   withArgsTests
    )
    set_tests_properties(${noArgsTests}   PROPERTIES TIMEOUT 10)
    set_tests_properties(${withArgsTests} PROPERTIES TIMEOUT 20)

  For backward compatibility, the following form is also supported::

    gtest_add_tests(exe args files...)

  ``exe``
    The path to the test executable or the name of a CMake target.
  ``args``
    A ;-list of extra arguments to be passed to executable.  The entire
    list must be passed as a single argument.  Enclose it in quotes,
    or pass ``""`` for no arguments.
  ``files...``
    A list of source files to search for tests and test fixtures.
    Alternatively, use ``AUTO`` to specify that ``exe`` is the name
    of a CMake executable target whose sources should be scanned.

  .. code-block:: cmake

    include(GoogleTest)
    set(FooTestArgs --foo 1 --bar 2)
    add_executable(FooTest FooUnitTest.cxx)
    gtest_add_tests(FooTest "${FooTestArgs}" AUTO)

.. command:: gtest_discover_tests

  Automatically add tests with CTest by querying the compiled test executable
  for available tests::

    gtest_discover_tests(target
                         [EXTRA_ARGS args...]
                         [WORKING_DIRECTORY dir]
                         [TEST_PREFIX prefix]
                         [TEST_SUFFIX suffix]
                         [TEST_FILTER expr]
                         [NO_PRETTY_TYPES] [NO_PRETTY_VALUES]
                         [PROPERTIES name1 value1...]
                         [TEST_LIST var]
                         [DISCOVERY_TIMEOUT seconds]
                         [XML_OUTPUT_DIR dir]
                         [DISCOVERY_MODE <POST_BUILD|PRE_TEST>]
                         [DISCOVERY_EXTRA_ARGS args...]
    )

  .. versionadded:: 3.10

  ``gtest_discover_tests()`` sets up a post-build or pre-test command on the
  test executable that generates the list of tests by parsing the output from
  running the test executable with the ``--gtest_list_tests`` argument.
  Compared to the source parsing approach of :command:`gtest_add_tests`,
  this ensures that the full list of tests, including instantiations of
  parameterized tests, is obtained.  Since test discovery occurs at build
  or test time, it is not necessary to re-run CMake when the list of tests
  changes.  However, it requires that :prop_tgt:`CROSSCOMPILING_EMULATOR`
  is properly set in order to function in a cross-compiling environment.

  Additionally, setting properties on tests is somewhat less convenient, since
  the tests are not available at CMake time.  Additional test properties may be
  assigned to the set of tests as a whole using the ``PROPERTIES`` option.  If
  more fine-grained test control is needed, custom content may be provided
  through an external CTest script using the :prop_dir:`TEST_INCLUDE_FILES`
  directory property.  The set of discovered tests is made accessible to such a
  script via the ``<target>_TESTS`` variable (see the ``TEST_LIST`` option
  below for further discussion and limitations).

  The options are:

  ``target``
    Specifies the Google Test executable, which must be a known CMake
    executable target.  CMake will substitute the location of the built
    executable when running the test.

  ``EXTRA_ARGS args...``
    Any extra arguments to pass on the command line to each test case.

    .. versionchanged:: 3.31
      Empty values in ``args...`` are preserved, see :policy:`CMP0178`.

  ``WORKING_DIRECTORY dir``
    Specifies the directory in which to run the discovered test cases.  If this
    option is not provided, the current binary directory is used.

  ``TEST_PREFIX prefix``
    Specifies a ``prefix`` to be prepended to the name of each discovered test
    case.  This can be useful when the same test executable is being used in
    multiple calls to ``gtest_discover_tests()`` but with different
    ``EXTRA_ARGS``.

  ``TEST_SUFFIX suffix``
    Similar to ``TEST_PREFIX`` except the ``suffix`` is appended to the name of
    every discovered test case.  Both ``TEST_PREFIX`` and ``TEST_SUFFIX`` may
    be specified.

  ``TEST_FILTER expr``
    .. versionadded:: 3.22

    Filter expression to pass as a ``--gtest_filter`` argument during test
    discovery.  Note that the expression is a wildcard-based format that
    matches against the original test names as used by gtest.  For type or
    value-parameterized tests, these names may be different to the potentially
    pretty-printed test names that :program:`ctest` uses.

  ``NO_PRETTY_TYPES``
    By default, the type index of type-parameterized tests is replaced by the
    actual type name in the CTest test name.  If this behavior is undesirable
    (e.g. because the type names are unwieldy), this option will suppress this
    behavior.

  ``NO_PRETTY_VALUES``
    By default, the value index of value-parameterized tests is replaced by the
    actual value in the CTest test name.  If this behavior is undesirable
    (e.g. because the value strings are unwieldy), this option will suppress
    this behavior.

  ``PROPERTIES name1 value1...``
    Specifies additional properties to be set on all tests discovered by this
    invocation of ``gtest_discover_tests()``.

  ``TEST_LIST var``
    Make the list of tests available in the variable ``var``, rather than the
    default ``<target>_TESTS``.  This can be useful when the same test
    executable is being used in multiple calls to ``gtest_discover_tests()``.
    Note that this variable is only available in CTest.

    Due to a limitation of CMake's parsing rules, any test with a square
    bracket in its name will be omitted from the list of tests stored in
    this variable.  Such tests will still be defined and executed by
    ``ctest`` as normal though.

  ``DISCOVERY_TIMEOUT num``
    .. versionadded:: 3.10.3

    Specifies how long (in seconds) CMake will wait for the test to enumerate
    available tests.  If the test takes longer than this, discovery (and your
    build) will fail.  Most test executables will enumerate their tests very
    quickly, but under some exceptional circumstances, a test may require a
    longer timeout.  The default is 5.  See also the ``TIMEOUT`` option of
    :command:`execute_process`.

    .. note::

      In CMake versions 3.10.1 and 3.10.2, this option was called ``TIMEOUT``.
      This clashed with the ``TIMEOUT`` test property, which is one of the
      common properties that would be set with the ``PROPERTIES`` keyword,
      usually leading to legal but unintended behavior.  The keyword was
      changed to ``DISCOVERY_TIMEOUT`` in CMake 3.10.3 to address this
      problem.  The ambiguous behavior of the ``TIMEOUT`` keyword in 3.10.1
      and 3.10.2 has not been preserved.

  ``XML_OUTPUT_DIR dir``
    .. versionadded:: 3.18

    If specified, the parameter is passed along with ``--gtest_output=xml:``
    to test executable. The actual file name is the same as the test target,
    including prefix and suffix. This should be used instead of
    ``EXTRA_ARGS --gtest_output=xml`` to avoid race conditions writing the
    XML result output when using parallel test execution.

  ``DISCOVERY_MODE``
    .. versionadded:: 3.18

    Provides greater control over when ``gtest_discover_tests()`` performs test
    discovery. By default, ``POST_BUILD`` sets up a post-build command
    to perform test discovery at build time. In certain scenarios, like
    cross-compiling, this ``POST_BUILD`` behavior is not desirable.
    By contrast, ``PRE_TEST`` delays test discovery until just prior to test
    execution. This way test discovery occurs in the target environment
    where the test has a better chance at finding appropriate runtime
    dependencies.

    ``DISCOVERY_MODE`` defaults to the value of the
    ``CMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE`` variable if it is not
    passed when calling ``gtest_discover_tests()``. This provides a mechanism
    for globally selecting a preferred test discovery behavior without having
    to modify each call site.

  ``DISCOVERY_EXTRA_ARGS args...``
    .. versionadded:: 3.31

    Any extra arguments to pass on the command line for the discovery command.

  .. versionadded:: 3.29
    The :prop_tgt:`TEST_LAUNCHER` target property is honored during test
    discovery and test execution.

  .. versionchanged:: 3.31
    Empty values in the :prop_tgt:`TEST_LAUNCHER` and
    :prop_tgt:`CROSSCOMPILING_EMULATOR` target properties are preserved,
    see policy :policy:`CMP0178`.

#]=======================================================================]

# Save project's policies
block(SCOPE_FOR POLICIES)
cmake_policy(VERSION 3.30)

#------------------------------------------------------------------------------
function(gtest_add_tests)

  if (ARGC LESS 1)
    message(FATAL_ERROR "No arguments supplied to gtest_add_tests()")
  endif()

  set(options
      SKIP_DEPENDENCY
  )
  set(oneValueArgs
      TARGET
      WORKING_DIRECTORY
      TEST_PREFIX
      TEST_SUFFIX
      TEST_LIST
  )
  set(multiValueArgs
      SOURCES
      EXTRA_ARGS
  )
  set(allKeywords ${options} ${oneValueArgs} ${multiValueArgs})

  cmake_policy(GET CMP0178 cmp0178
    PARENT_SCOPE # undocumented, do not use outside of CMake
  )

  unset(sources)
  if("${ARGV0}" IN_LIST allKeywords)
    if(cmp0178 STREQUAL "NEW")
      cmake_parse_arguments(PARSE_ARGV 0 arg
        "${options}" "${oneValueArgs}" "${multiValueArgs}"
      )
    else()
      cmake_parse_arguments(arg "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
      if(NOT cmp0178 STREQUAL "OLD")
        block(SCOPE_FOR VARIABLES)
          cmake_parse_arguments(PARSE_ARGV 0 arg_new
            "${options}" "${oneValueArgs}" "${multiValueArgs}"
          )
          # Due to a quirk of cmake_parse_arguments(PARSE_ARGV),
          # arg_new_EXTRA_ARGS will have semicolons already escaped, but
          # arg_EXTRA_ARGS won't. We need to pass the former through one round
          # of command argument parsing to de-escape them for comparison with
          # the latter.
          set(__newArgs ${arg_new_EXTRA_ARGS})
          if(NOT "${arg_EXTRA_ARGS}" STREQUAL "${__newArgs}")
            cmake_policy(GET_WARNING CMP0178 cmp0178_warning)
            message(AUTHOR_WARNING
              "The EXTRA_ARGS contain one or more empty values. Those empty "
              "values are being silently discarded to preserve backward "
              "compatibility.\n"
              "${cmp0178_warning}"
            )
          endif()
        endblock()
      endif()
    endif()
    set(autoAddSources YES)
  else()
    # Non-keyword syntax, convert to keyword form
    if (ARGC LESS 3)
      message(FATAL_ERROR "gtest_add_tests() without keyword options requires at least 3 arguments")
    endif()
    set(arg_TARGET     "${ARGV0}")
    set(arg_EXTRA_ARGS "${ARGV1}")
    if(NOT "${ARGV2}" STREQUAL "AUTO")
      set(arg_SOURCES "${ARGV}")
      list(REMOVE_AT arg_SOURCES 0 1)
    endif()
  endif()

  # The non-keyword syntax allows the first argument to be an arbitrary
  # executable rather than a target if source files are also provided. In all
  # other cases, both forms require a target.
  if(NOT TARGET "${arg_TARGET}" AND NOT arg_SOURCES)
    message(FATAL_ERROR "${arg_TARGET} does not define an existing CMake target")
  endif()
  if(NOT arg_WORKING_DIRECTORY)
    unset(workDir)
  else()
    set(workDir WORKING_DIRECTORY "${arg_WORKING_DIRECTORY}")
  endif()

  if(NOT arg_SOURCES)
    get_property(arg_SOURCES TARGET ${arg_TARGET} PROPERTY SOURCES)
  endif()

  unset(testList)

  set(gtest_case_name_regex ".*\\([ \r\n\t]*([A-Za-z_0-9]+)[ \r\n\t]*,[ \r\n\t]*([A-Za-z_0-9]+)[ \r\n\t]*\\).*")
  set(gtest_test_type_regex "(TYPED_TEST|TEST)_?[FP]?")
  set(each_line_regex "([^\r\n]*[\r\n])")

  foreach(source IN LISTS arg_SOURCES)
    if(NOT arg_SKIP_DEPENDENCY)
      set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${source})
    endif()
    file(READ "${source}" contents)
    # Replace characters in file content that are special to CMake
    string(REPLACE "[" "<OPEN_BRACKET>" contents "${contents}")
    string(REPLACE "]" "<CLOSE_BRACKET>" contents "${contents}")
    string(REPLACE ";" "\\;" contents "${contents}")
    # Split into lines
    string(REGEX MATCHALL "${each_line_regex}" content_lines "${contents}")
    set(line "0")
    # Stores the line number of the start of a test definition
    set(accumulate_line "0")
    # Stores accumulated lines to match multi-line test definitions
    set(accumulated "")
    # Iterate over each line in the file so that we know the line number of a test definition
    foreach(line_str IN LISTS content_lines)
      MATH(EXPR line "${line}+1")
      # Check if the current line is the start of a test definition
      string(REGEX MATCH "[ \t]*${gtest_test_type_regex}[ \t]*[\\(]*" accumlate_start_hit "${line_str}")
      if(accumlate_start_hit)
        set(accumulate_line "${line}")
      endif()
      # Append the current line to the accumulated string
      set(accumulated "${accumulated}${line_str}")
      # Attempt to match a complete test definition in the accumulated string
      string(REGEX MATCH "${gtest_test_type_regex}[ \r\n\t]*\\(([A-Za-z_0-9 ,\r\n\t]+)\\)" hit "${accumulated}")
      if(hit)
        # Reset accumulated for the next match
        set(accumulated "")
      else()
        # Continue accumulating lines
        continue()
      endif()
      # At this point, the start line of the test definition is known
      # Hence, we can set the test's DEF_SOURCE_LINE property with
      # ${source}:${accumulate_line} below.
      # VS Code CMake Tools extension looks for DEF_SOURCE_LINE
      # to locate the test definition for its "Go to test" feature.

      string(REGEX MATCH "${gtest_test_type_regex}" test_type ${hit})

      # Parameterized tests have a different signature for the filter
      if("x${test_type}" STREQUAL "xTEST_P")
        string(REGEX REPLACE ${gtest_case_name_regex} "*/\\1.\\2/*" gtest_test_name ${hit})
      elseif("x${test_type}" STREQUAL "xTYPED_TEST_P")
        string(REGEX REPLACE ${gtest_case_name_regex} "*/\\1/*.\\2" gtest_test_name ${hit})
      elseif("x${test_type}" STREQUAL "xTEST_F" OR "x${test_type}" STREQUAL "xTEST")
        string(REGEX REPLACE ${gtest_case_name_regex} "\\1.\\2" gtest_test_name ${hit})
      elseif("x${test_type}" STREQUAL "xTYPED_TEST")
        string(REGEX REPLACE ${gtest_case_name_regex} "\\1/*.\\2" gtest_test_name ${hit})
      else()
        message(WARNING "Could not parse GTest ${hit} for adding to CTest.")
        continue()
      endif()

      set(extra_args "")
      foreach(arg IN LISTS arg_EXTRA_ARGS)
        string(APPEND extra_args " [==[${arg}]==]")
      endforeach()

      # Make sure tests disabled in GTest get disabled in CTest
      if(gtest_test_name MATCHES "(^|\\.)DISABLED_")
        # Add the disabled test if CMake is new enough
        # Note that this check is to allow backwards compatibility so this
        # module can be copied locally in projects to use with older CMake
        # versions
        if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.8.20170401)
          string(REGEX REPLACE
                 "(^|\\.)DISABLED_" "\\1"
                 orig_test_name "${gtest_test_name}"
          )
          set(ctest_test_name
              ${arg_TEST_PREFIX}${orig_test_name}${arg_TEST_SUFFIX}
          )
          cmake_language(EVAL CODE "
            add_test(NAME ${ctest_test_name}
                     ${workDir}
                     COMMAND ${arg_TARGET}
                       --gtest_also_run_disabled_tests
                       --gtest_filter=${gtest_test_name}
                       ${extra_args}
                     __CMP0178 [==[${cmp0178}]==]
            )"
          )
          set_tests_properties(${ctest_test_name} PROPERTIES DISABLED TRUE
            DEF_SOURCE_LINE "${source}:${accumulate_line}")
          list(APPEND testList ${ctest_test_name})
        endif()
      else()
        set(ctest_test_name ${arg_TEST_PREFIX}${gtest_test_name}${arg_TEST_SUFFIX})
        cmake_language(EVAL CODE "
          add_test(NAME ${ctest_test_name}
                   ${workDir}
                   COMMAND ${arg_TARGET}
                     --gtest_filter=${gtest_test_name}
                     ${extra_args}
                   __CMP0178 [==[${cmp0178}]==]
          )"
        )
        # Makes sure a skipped GTest is reported as so by CTest
        set_tests_properties(
          ${ctest_test_name}
          PROPERTIES
          SKIP_REGULAR_EXPRESSION "\\[  SKIPPED \\]"
          DEF_SOURCE_LINE "${source}:${accumulate_line}"
        )
        list(APPEND testList ${ctest_test_name})
      endif()
    endforeach()
  endforeach()

  if(arg_TEST_LIST)
    set(${arg_TEST_LIST} ${testList} PARENT_SCOPE)
  endif()

endfunction()

#------------------------------------------------------------------------------

function(gtest_discover_tests target)
  set(options
    NO_PRETTY_TYPES
    NO_PRETTY_VALUES
  )
  set(oneValueArgs
    TEST_PREFIX
    TEST_SUFFIX
    WORKING_DIRECTORY
    TEST_LIST
    DISCOVERY_TIMEOUT
    XML_OUTPUT_DIR
    DISCOVERY_MODE
  )
  set(multiValueArgs
    EXTRA_ARGS
    DISCOVERY_EXTRA_ARGS
    PROPERTIES
    TEST_FILTER
  )
  cmake_parse_arguments(PARSE_ARGV 1 arg
    "${options}" "${oneValueArgs}" "${multiValueArgs}"
  )

  if(NOT arg_WORKING_DIRECTORY)
    set(arg_WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
  endif()
  if(NOT arg_TEST_LIST)
    set(arg_TEST_LIST ${target}_TESTS)
  endif()
  if(NOT arg_DISCOVERY_TIMEOUT)
    set(arg_DISCOVERY_TIMEOUT 5)
  endif()
  if(NOT arg_DISCOVERY_MODE)
    if(NOT CMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE)
      set(CMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE "POST_BUILD")
    endif()
    set(arg_DISCOVERY_MODE ${CMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE})
  endif()

  get_property(
    has_counter
    TARGET ${target}
    PROPERTY CTEST_DISCOVERED_TEST_COUNTER
    SET
  )
  if(has_counter)
    get_property(
      counter
      TARGET ${target}
      PROPERTY CTEST_DISCOVERED_TEST_COUNTER
    )
    math(EXPR counter "${counter} + 1")
  else()
    set(counter 1)
  endif()
  set_property(
    TARGET ${target}
    PROPERTY CTEST_DISCOVERED_TEST_COUNTER
    ${counter}
  )

  # Define rule to generate test list for aforementioned test executable
  set(ctest_file_base "${CMAKE_CURRENT_BINARY_DIR}/${target}[${counter}]")
  set(ctest_include_file "${ctest_file_base}_include.cmake")
  set(ctest_tests_file "${ctest_file_base}_tests.cmake")
  get_property(test_launcher
    TARGET ${target}
    PROPERTY TEST_LAUNCHER
  )
  cmake_policy(GET CMP0158 _CMP0158
    PARENT_SCOPE # undocumented, do not use outside of CMake
  )
  if(NOT _CMP0158 OR _CMP0158 STREQUAL "OLD" OR _CMP0158 STREQUAL "NEW" AND CMAKE_CROSSCOMPILING)
    get_property(crosscompiling_emulator
      TARGET ${target}
      PROPERTY CROSSCOMPILING_EMULATOR
    )
  endif()

  if(test_launcher AND crosscompiling_emulator)
    set(test_executor "${test_launcher}" "${crosscompiling_emulator}")
  elseif(test_launcher)
    set(test_executor "${test_launcher}")
  elseif(crosscompiling_emulator)
    set(test_executor "${crosscompiling_emulator}")
  else()
    set(test_executor "")
  endif()

  cmake_policy(GET CMP0178 cmp0178
    PARENT_SCOPE # undocumented, do not use outside of CMake
  )
  if(NOT cmp0178 STREQUAL "NEW")
    # Preserve old behavior where empty list items are silently discarded
    set(test_executor_orig "${test_executor}")
    set(test_executor ${test_executor})
    set(arg_EXTRA_ARGS_orig "${arg_EXTRA_ARGS}")
    set(arg_EXTRA_ARGS ${arg_EXTRA_ARGS})
    if(NOT cmp0178 STREQUAL "OLD")
      if(NOT "${test_executor}" STREQUAL "${test_executor_orig}")
        cmake_policy(GET_WARNING CMP0178 cmp0178_warning)
        message(AUTHOR_WARNING
          "The '${target}' target's TEST_LAUNCHER or CROSSCOMPILING_EMULATOR "
          "test properties contain one or more empty values. Those empty "
          "values are being silently discarded to preserve backward "
          "compatibility.\n"
          "${cmp0178_warning}"
        )
      endif()
      if(NOT "${arg_EXTRA_ARGS}" STREQUAL "${arg_EXTRA_ARGS_orig}")
        cmake_policy(GET_WARNING CMP0178 cmp0178_warning)
        message(AUTHOR_WARNING
          "The EXTRA_ARGS value contains one or more empty values. "
          "Those empty values are being silently discarded to preserve "
          "backward compatibility.\n"
          "${cmp0178_warning}"
        )
      endif()
    endif()
  endif()

  if(arg_DISCOVERY_MODE STREQUAL "POST_BUILD")
    add_custom_command(
      TARGET ${target} POST_BUILD
      BYPRODUCTS "${ctest_tests_file}"
      COMMAND "${CMAKE_COMMAND}"
              -D "TEST_TARGET=${target}"
              -D "TEST_EXECUTABLE=$<TARGET_FILE:${target}>"
              -D "TEST_EXECUTOR=${test_executor}"
              -D "TEST_WORKING_DIR=${arg_WORKING_DIRECTORY}"
              -D "TEST_EXTRA_ARGS=${arg_EXTRA_ARGS}"
              -D "TEST_PROPERTIES=${arg_PROPERTIES}"
              -D "TEST_PREFIX=${arg_TEST_PREFIX}"
              -D "TEST_SUFFIX=${arg_TEST_SUFFIX}"
              -D "TEST_FILTER=${arg_TEST_FILTER}"
              -D "NO_PRETTY_TYPES=${arg_NO_PRETTY_TYPES}"
              -D "NO_PRETTY_VALUES=${arg_NO_PRETTY_VALUES}"
              -D "TEST_LIST=${arg_TEST_LIST}"
              -D "CTEST_FILE=${ctest_tests_file}"
              -D "TEST_DISCOVERY_TIMEOUT=${arg_DISCOVERY_TIMEOUT}"
              -D "TEST_DISCOVERY_EXTRA_ARGS=${arg_DISCOVERY_EXTRA_ARGS}"
              -D "TEST_XML_OUTPUT_DIR=${arg_XML_OUTPUT_DIR}"
              -P "${CMAKE_ROOT}/Modules/GoogleTestAddTests.cmake"
      VERBATIM
    )

    file(WRITE "${ctest_include_file}"
      "if(EXISTS \"${ctest_tests_file}\")\n"
      "  include(\"${ctest_tests_file}\")\n"
      "else()\n"
      "  add_test(${target}_NOT_BUILT ${target}_NOT_BUILT)\n"
      "endif()\n"
    )
  elseif(arg_DISCOVERY_MODE STREQUAL "PRE_TEST")

    get_property(GENERATOR_IS_MULTI_CONFIG GLOBAL
        PROPERTY GENERATOR_IS_MULTI_CONFIG
    )

    if(GENERATOR_IS_MULTI_CONFIG)
      set(ctest_tests_file "${ctest_file_base}_tests-$<CONFIG>.cmake")
    endif()

    string(CONCAT ctest_include_content
      "if(EXISTS \"$<TARGET_FILE:${target}>\")"                                    "\n"
      "  if(NOT EXISTS \"${ctest_tests_file}\" OR"                                 "\n"
      "     NOT \"${ctest_tests_file}\" IS_NEWER_THAN \"$<TARGET_FILE:${target}>\" OR\n"
      "     NOT \"${ctest_tests_file}\" IS_NEWER_THAN \"\${CMAKE_CURRENT_LIST_FILE}\")\n"
      "    include(\"${CMAKE_ROOT}/Modules/GoogleTestAddTests.cmake\")"            "\n"
      "    gtest_discover_tests_impl("                                             "\n"
      "      TEST_EXECUTABLE"        " [==[$<TARGET_FILE:${target}>]==]"           "\n"
      "      TEST_EXECUTOR"          " [==[${test_executor}]==]"                   "\n"
      "      TEST_WORKING_DIR"       " [==[${arg_WORKING_DIRECTORY}]==]"           "\n"
      "      TEST_EXTRA_ARGS"        " [==[${arg_EXTRA_ARGS}]==]"                  "\n"
      "      TEST_PROPERTIES"        " [==[${arg_PROPERTIES}]==]"                  "\n"
      "      TEST_PREFIX"            " [==[${arg_TEST_PREFIX}]==]"                 "\n"
      "      TEST_SUFFIX"            " [==[${arg_TEST_SUFFIX}]==]"                 "\n"
      "      TEST_FILTER"            " [==[${arg_TEST_FILTER}]==]"                 "\n"
      "      NO_PRETTY_TYPES"        " [==[${arg_NO_PRETTY_TYPES}]==]"             "\n"
      "      NO_PRETTY_VALUES"       " [==[${arg_NO_PRETTY_VALUES}]==]"            "\n"
      "      TEST_LIST"              " [==[${arg_TEST_LIST}]==]"                   "\n"
      "      CTEST_FILE"             " [==[${ctest_tests_file}]==]"                "\n"
      "      TEST_DISCOVERY_TIMEOUT" " [==[${arg_DISCOVERY_TIMEOUT}]==]"           "\n"
      "      TEST_DISCOVERY_EXTRA_ARGS [==[${arg_DISCOVERY_EXTRA_ARGS}]==]"        "\n"
      "      TEST_XML_OUTPUT_DIR"    " [==[${arg_XML_OUTPUT_DIR}]==]"              "\n"
      "    )"                                                                      "\n"
      "  endif()"                                                                  "\n"
      "  include(\"${ctest_tests_file}\")"                                         "\n"
      "else()"                                                                     "\n"
      "  add_test(${target}_NOT_BUILT ${target}_NOT_BUILT)"                        "\n"
      "endif()"                                                                    "\n"
    )

    if(GENERATOR_IS_MULTI_CONFIG)
      foreach(_config ${CMAKE_CONFIGURATION_TYPES})
        file(GENERATE
          OUTPUT "${ctest_file_base}_include-${_config}.cmake"
          CONTENT "${ctest_include_content}"
          CONDITION $<CONFIG:${_config}>
        )
      endforeach()
      file(WRITE "${ctest_include_file}"
        "include(\"${ctest_file_base}_include-\${CTEST_CONFIGURATION_TYPE}.cmake\")"
      )
    else()
      file(GENERATE
        OUTPUT "${ctest_file_base}_include.cmake"
        CONTENT "${ctest_include_content}"
      )
      file(WRITE "${ctest_include_file}"
        "include(\"${ctest_file_base}_include.cmake\")"
      )
    endif()

  else()
    message(FATAL_ERROR "Unknown DISCOVERY_MODE: ${arg_DISCOVERY_MODE}")
  endif()

  # Add discovered tests to directory TEST_INCLUDE_FILES
  set_property(DIRECTORY
    APPEND PROPERTY TEST_INCLUDE_FILES "${ctest_include_file}"
  )

endfunction()

###############################################################################

# Restore project's policies
endblock()