Minimalistically building a test for a simple header using CMake

Question

I have a C++ header which contains a class with a method like below. Lets say its a header only library I have.

// MyHeader.hpp #pragma once #include <string> namespace myheaderonlylibrary { class MyClass { public: unsigned int Func1(const std::string& str) { if (!str.empty()) return 10; else return 0; } }; }

To test the above method I heve the following gtest source file inside a folder called unittest which is like the convention followed.

// MyTests.cpp #include <limits.h> #include "gtest/gtest.h" #include "../MyHeader.hpp" TEST(MyTest, Test_Something) { myheaderonlylibrary::MyClass my_object; unsigned int expected_value = 0; EXPECT_EQ(expected_value, my_object.Func1("")); }

All I want to do is build the test using Cmake and run the test. So, following is my CMakeLists.txt.

// CMakeLists.txt cmake_minimum_required(VERSION 3.4) set(MyheaderOnlyLibrary_HEADERS MyHeader.hpp ) set(MyheaderOnlyLibrary_unittest unittest/MyTests.cpp ) find_package(GTest REQUIRED) enable_testing () add_executable(MyheaderOnlyLibraryTests ${MyheaderOnlyLibrary_unittest})

After the above is set, I do a cmake .. and make which results with the following error.

"_main", referenced from: implicit entry/start for main executable ld: symbol(s) not found for architecture x86_64

Question:
I am not a pro in CMake. My question is that if all I want to do is to be able run tests, then should I be doing an add_executable? Is this correct approach when the only thing I want is to build and run the tests? Seems like the error when calling make is because add_executable is looking for main method like in a normal executable and its not finding it.

What is the correct way to build a test only project where a header file is the only thing to be tested?

How to run the tests after building? Looks like there is a command CTest to run the tests built using CMake?

Environment:
I am building this on a macOS with clang as the compiler with C++11.

crdrisko · Accepted Answer · 2020-08-17 16:00:16Z

Just like a normal C++ program you need to have a main function to execute, for a googletest unit test you can use the following:

int main(int argc, char** argv) { testing::InitGoogleTest(&argc, argv); return RUN_ALL_TESTS(); }

This will run your TEST function when executed.

To use ctest to actually run your tests you should have the following lines in your cmake file:

find_package(GTest) include_directories(${GTEST_INCLUDE_DIRS}) include(CTest) include(GoogleTest) enable_testing() target_link_libraries(testName ${GTEST_LIBRARIES}) gtest_discover_tests(testName)

EDIT: As an easier place to start before jumping into cmake, I would recommend you start with compiling and running your command on the command line. You can do that with the following:

g++ unittest/myunittest.cpp -o unittest/myunittest.out -lgtest -std=c++11 ./unittest/myunittest.out

Once you know it works, take a look at cmake’s documentation and reproduce your results with a cmake file. Then you can start to scale up your programs. Understanding how to run these commands through the command line will give you an appreciation and a better understanding of what cmake is doing.

Yes, you can run it the same way as a normal application or use the ctest command as you eluded to
Yes you need to link the googletest libraries, cmake can handle this with the lines I added in my edit, you may need to use a higher version of cmake to have access to the gtest_discover_tests function
Yes, that was just a placeholder for your actual test name, MyHeaderOnlyLibraryTest
Instead of gtest_discover_tests() try gtest_add_tests(). That was the predecessor of discover tests pre-version 3.10. Alternatively, see my edit for building at the command line first

Collectives™ on Stack Overflow

Minimalistically building a test for a simple header using CMake

1 Answer 1

10 Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

10 Comments

Related