A barebones C++ library template using CMake and Google Test

Objective

This is a BAREBONES C++ template with Google Test support using CMake. It is setup to allow for the building of a static library using TDD principles; but could be adapted for building a small program. This is in no way the ideal solution.

This template was created to allow for programming under Mac OS. But the files should work under other systems.

Directory Structure

This is the structure that we start with. It should be noted that the build directory will be generated in the root of this structure under VSCode. This appears, to generally be discouraged and can be changed with some configuration options that I will not go into here.

❯ tree .
.
├── CMakeLists.txt
├── README.md
├── src
│   ├── CMakeLists.txt
│   ├── Example.cpp
│   └── Example.hpp
└── tests
    ├── CMakeLists.txt
    └── lib-tester.cpp

Requirements

You will require the following items to be installed. Note that I have used homebrew in order to source the requirements. If you are not using Mac OS you should be able to find other ways to install the requirements. Google Search will be your friend in this.

CMake

Installation

brew install cmake

Google Test

Installation

brew install googletest

Example Execution

Let's build the code in and Out of Source build folder.

❯ cmake -B /tmp/testing -S .
-- The CXX compiler identification is AppleClang 13.0.0.13000029
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found GTest: /usr/local/lib/cmake/GTest/GTestConfig.cmake (found version "1.11.0")  
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/testing

Let's compile the code

❯ cd /tmp/testing
❯ ls
CMakeCache.txt      CTestTestfile.cmake cmake_install.cmake tests
CMakeFiles          Makefile            src
❯ make
[ 25%] Building CXX object src/CMakeFiles/mylib.dir/EXample.cpp.o
[ 50%] Linking CXX static library libmylib.a
[ 50%] Built target mylib
[ 75%] Building CXX object tests/CMakeFiles/Test1Tester.dir/lib-tester.cpp.o
[100%] Linking CXX executable Test1Tester
[100%] Built target Test1Tester

Things to note: The generated static library will be called libmylib.a and its name comes from the project variable in the top level CMakeList.txt file.

CMakeList.txt Contents

Root

cmake_minimum_required(VERSION 3.22)
project(mylib
        VERSION 0.1.0.0
        DESCRIPTION "What does it do?"
        LANGUAGES CXX
        )

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED true)
set(CMAKE_POSTION_INDEPENDENT_CODE ON)

enable_testing()

add_subdirectory(src)
add_subdirectory(tests)

The project label here is being used to set several variables.

• mylib This is used to set the library's name -> libmylib.a
• enable_testing() This is used to enable to testing within the IDE
• add_subdirectory() This makes the top level aware of the sub-directories. src is the code source of the library. And tests is where the source code for the testing code will be written.

src

set(LIB_BINARY ${CMAKE_PROJECT_NAME})

set(headers
    Example.hpp)
set(sources
    EXample.cpp)
set(SOURCES ${headers} ${sources})

add_library(${LIB_BINARY} STATIC ${SOURCES})
target_include_directories( ${LIB_BINARY} PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

• LIB_BINARY This stores the name of the library to be generated. Coming from project which was set in the previous CMakeList.txt covered earlier.
• headers This will contain references to any and all header files that are need to compile the library.
• sources This will contain references to any source files that are needed.
• SOURCES This combines headers and sources
• add_library This tells cmake that we are declaring we want to generate a library file and not an executable. We also specifiy that it is to be a Static and not dynamic library.
• target_include_directories this tells cmake that we should:
  • build a library named lib{LIB_BINARY}.a
  • This directory's contents should be made available to other directories in the main project. This means we will be able to build the test programs using this new library.

tests

cmake_minimum_required(VERSION 3.22)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED true)
set(CMAKE_POSTION_INDEPENDENT_CODE ON)

file(GLOB_RECURSE TEST_SOURCES LIST_DIRECTORIES false *.hpp *.cpp)

set(test1 Test1Tester)
set(test1src lib-tester.cpp)

# Specify second test program and source files
#set(test2 Test2Tester)
#set(test2src lib-tester2.cpp)

add_executable(${test1} ${test1src})

# Specify executable for second tester
#add_executable(${test2} ${test2src})

find_package( GTest REQUIRED )      
# adds the gtest include directory
include_directories( ${GTEST_INCLUDE_DIRS} )
# links gtest
target_link_libraries( ${test1} LINK_PUBLIC ${GTEST_LIBRARIES} ${CMAKE_PROJECT_NAME})

# Specify target for second test program
#target_link_libraries( ${test2} LINK_PUBLIC ${GTEST_LIBRARIES} ${CMAKE_PROJECT_NAME})

enable_testing()
add_test(
   NAME ${test1}}
   COMMAND ${test1}
)

• file This another way to get gather the files for compiling. Though it is discouraged.
• test1 This will hold the name of the testing executable.
• test1src This holds the name of the source file to be used to build the test executable.
• add_executable This is the executable to be compiled as the test program

We also need to ensure that we can link in the GTest library. We do that with the following commands.

find_package( GTest REQUIRED )      
# adds the gtest include directory
include_directories( ${GTEST_INCLUDE_DIRS} )

• This locates the Google Test libraries that were installed earlier.

Linking the everything together so we have an executable that tests our code.

target_link_libraries( ${test1} LINK_PUBLIC ${GTEST_LIBRARIES} ${CMAKE_PROJECT_NAME})

• This creates the executable, linking the GTEST library and the mylib library

If you look through you will see that I have commented out a second source and executable. It is possible to build several test programs. This allows you to build different tests programs instead of having one single monalithic test application.

Screen Capture

Github Repo

You can get the source here