c++ - How to use CMake with Catch2?

Question

From Catch2's example, I tried to run this example with cmake where structure of my project is like this:

/factorial
    +-- CMakeLists.txt
    +-- /bin
    +-- /include
    |     +-- catch.hpp
    |     +-- fact.hpp 
    +-- /src
    |     +-- CMakeLists.txt
    |    +-- fact.cpp
    +-- /test
         +-- CMakeLists.txt
         +-- test_fact.cpp

fact.cpp:

unsigned int factorial( unsigned int number ) {
    return number <= 1 ? number : factorial(number-1)*number;
}

fact.hpp:

#ifndef FACT_H
#define FACT_H

unsigned int factorial(unsigned int);

#endif

test_fact.cpp:

#define CATCH_CONFIG_MAIN
#include "catch.hpp"
#include "fact.hpp"

TEST_CASE( "factorials are computed", "[factorial]" ) {
    REQUIRE( factorial(1) == 1 );
    REQUIRE( factorial(2) == 2 );
    REQUIRE( factorial(3) == 6 );
    REQUIRE( factorial(10) == 3628800 );
}

I tried several ways already to build this project with cmake but it's failed. Sometimes I got an error:

cpp:X:XX: fatal error: 'fact.hpp' file not found
...

and sometimes I got:

Undefined symbols for architecture x86_64:
  "_main", referenced from:
...

when I run make.

What should I have in factorial/CMakeLists.txt,factorial/src/CMakeLists.txt and factorial/test/CMakeLists.txt, if I want to have my execution files in factorial/bin?

Additional: This is my CMakeLists.txts (I think they are completely wrong).

factorial/CMakeLists.txt:

project(factorial)
cmake_minimum_required(VERSION 2.8.12)

add_definitions("-std=c++11")
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)

add_subdirectory(src)
add_subdirectory(test)

factorial/src/CMakeLists.txt:

project(factorial)
cmake_minimum_required(VERSION 2.8.12)

add_executable(fact fact.cpp)

factorial/test/CMakeLists.txt:

project(factorial)
cmake_minimum_required(VERSION 2.8.12)

add_executable(test_fact test_fact.cpp)
target_include_directories(test_fact PRIVATE ${CMAKE_SOURCE_DIR}/include)

Answer 1

If you look at the CMake documentation, the PROJECT_SOURCE_DIR variable is define as that:

Top level source directory for the current project.

This is the source directory of the most recent project() command.

Since you called project many times, that variable will constantly change. I would suggest you to remove your project directive, or to use CMAKE_SOURCE_DIR, which always point to the source directory of the whole project.

---

As a side note, I suggest to use set(CMAKE_CXX_STANDARD 11) instead of add_definition