Try out GoogleTest to test a class and a C++ module

This week I'm going to learn GoogleTest for c++. I used JUnit frequently during my Java days. But never used a unit test framework (or unit tests) for embedded development.

Goals for the first days, done in Try out GoogleTest

able to run a GoogleTest
build a CMake script that does everything
integrate with VSCode

and, in this post

test some custom code: a class in a C++ module

Class interface

// test_module_interface.cpp

module;
#include <string_view>
export module test_module;

export namespace test_module {

class TestClass {
public:
  bool match(const std::string_view& sv);
};

} // namespace test_module

Class implementation

// test_module_impl.cpp

module;
#include <string_view>
module test_module;

namespace test_module {
bool TestClass::match(const std::string_view& sv) {
    using std::operator""sv;
    return ("match"sv.compare(sv) == 0);    
}

} // namespace test_module

Test Suite

// test_suite.cpp

#include <gtest/gtest.h>
import test_module;

TEST(string_view, match) {
    test_module::TestClass o;
    EXPECT_TRUE(o.match("match")); // should pass
}

TEST(string_view, missmatch) {
    test_module::TestClass o;
    EXPECT_FALSE(o.match("mismatch")); // should pass
}

CMake script

cmake_minimum_required(VERSION 3.28)

project(test_class_module C CXX ASM)

# GoogleTest requires at least C++14
set(CMAKE_CXX_STANDARD 26)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fmodules-ts")

include(FetchContent)
FetchContent_Declare(
  googletest
  URL https://github.com/google/googletest/archive/03597a01ee50ed33e9dfd640b249b4be3799d395.zip
)
# For Windows: Prevent overriding the parent project's compiler/linker settings
set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
FetchContent_MakeAvailable(googletest)

enable_testing()

add_executable(${CMAKE_PROJECT_NAME})
target_sources(${CMAKE_PROJECT_NAME}
        PRIVATE
        ${CMAKE_CURRENT_SOURCE_DIR}/test_suite.cpp
        ${CMAKE_CURRENT_SOURCE_DIR}/test_module_impl.cpp
)
target_sources(${CMAKE_PROJECT_NAME}
        PRIVATE
        FILE_SET cxx_modules TYPE CXX_MODULES FILES
        ${CMAKE_CURRENT_SOURCE_DIR}/test_module_iface.cpp

)

target_link_libraries( ${CMAKE_PROJECT_NAME}
        PRIVATE
        GTest::gtest_main
)

include(GoogleTest)
gtest_discover_tests(${CMAKE_PROJECT_NAME})

Result