The Goal
My goal is to create tests with googleTest that make use of MPI, add them via gtest_discover_tests(), and execute them via ctest.
I have seen posts where people use add_test to add the MPI executer manually to their tests (e.g. here) but gtest_discover_tests() (which is way handier) seems to not expose such an option. There exists the CROSSCOMPILING_EMULATOR property which can apparently be abused for this but this seems hacky (see here).
Minimal Example:
CMakeLists.txt:
cmake_minimum_required(VERSION 3.23)
project(TheProject)
set(CMAKE_CXX_STANDARD 17)
# get dependencies
include(FetchContent)
FetchContent_Declare(
googletest
URL https://github.com/google/googletest/archive/609281088cfefc76f9d0ce82e1ff6c30cc3591e5.zip
)
FetchContent_MakeAvailable(googletest)
find_package(MPI REQUIRED)
# define a exe
add_executable(TheExe main.cpp theTest.cpp)
target_link_libraries(TheExe PUBLIC gtest MPI::MPI_CXX)
# set up tests
enable_testing()
include(GoogleTest)
set_property(TARGET TheExe PROPERTY CROSSCOMPILING_EMULATOR '${MPIEXEC_EXECUTABLE} ${MPIEXEC_NUMPROC_FLAG} 3')
gtest_discover_tests(TheExe)
theTest.cpp: (some dummy tests)
#include <gtest/gtest.h>
#include <mpi.h>
TEST(HelloTest, TestA) {
int rank;
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
std::cout << rank << std::endl;
EXPECT_LT(rank, 1337);
}
TEST(HelloTest, TestB) {
MPI_Barrier(MPI_COMM_WORLD); // sync all ranks
EXPECT_EQ(42, 7*6);
}
main.cpp
#include <gtest/gtest.h>
#include <mpi.h>
int main(int argc, char **argv) {
testing::InitGoogleTest(&argc, argv);
MPI_Init(&argc, &argv);
auto result = RUN_ALL_TESTS();
MPI_Finalize();
return result;
}
Build via CMake and then execute with ctest. This appears to give the desired behavior, alas very verbose because we get the output of all ranks. There is also no way to make use of MPIEXEC_POSTFLAGS. However, at least for me, both of these points are secondary.
The Question
Is this is recommended / proper /best way to achieve the goal stated in the beginning??
