title: CMake unable to find boost_test
body: <p>On OSX, I have installed Boost using <code>brew install boost</code>, and I'm trying to link as follows:</p>
  
  <pre><code>cmake_minimum_required(VERSION 3.13)
  project(LinkBoost)
  
  set(CMAKE_CXX_STANDARD 14)
  
  add_executable(LinkBoost
      desmond.cpp
      desmond.h
      integration.cpp
      integration.h
      main.cpp
      main.h
      utillity.cpp
      utillity.h)
  
  list(APPEND CMAKE_PREFIX_PATH "/usr/local/Cellar/boost/1.69.0_2")
  set(Boost_ADDITIONAL_VERSIONS "1.69.0" "1.69")
  
  find_package(BoostCOMPONENTS filesystem system test REQUIRED)
  
  target_include_directories(LinkBoost PUBLIC ".")
  
  # adds include directories, definitions and link libraries
  target_link_libraries(VelocityDispersion PUBLIC
          Boost::filesystem Boost::system Boost::test)
  </code></pre>
  
  <p>This however gives me:</p>
  
  <pre><code>Unable to find the requested Boost libraries.
  
  Boost version: 1.69.0
  
  Boost include path: /usr/local/Cellar/boost/1.69.0_2/include
  
  Could not find the following Boost libraries:
  
        boost_test
  
  Some (but not all) of the required Boost libraries were found.  You may
  need to install these additional Boost libraries.  Alternatively, set
  BOOST_LIBRARYDIR to the directory containing Boost libraries or BOOST_ROOT
  to the location of Boost.
  </code></pre>
  
  <p>Can anyone help me understand what is going wrong here? I feel like it's something obvious that I'm missing...</p>