diff --git a/CMakeLists.txt b/CMakeLists.txt
index 463cbc4..d8c4951 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,13 +1,42 @@
 cmake_minimum_required(VERSION 3.7.2)
 
+if ("${CMAKE_BINARY_DIR}" STREQUAL "${CMAKE_SOURCE_DIR}")
+    message(FATAL_ERROR "In-source builds are disabled.
+    Please create a subfolder called build and use `cmake ..` inside it.
+    NOTE: cmake will now create CMakeCache.txt and CMakeFiles/*.
+          You must delete them, or cmake will refuse to work.")
+endif()
+set_property(DIRECTORY APPEND PROPERTY ADDITIONAL_MAKE_CLEAN_FILES "bin" "doc" "CMakeFiles" "lib" "include")
+
+
 project(GUI)
 set(CMAKE_CXX_STANDARD 14)
 
+set(CMAKE_CXX_CLANG_TIDY "clang-tidy;-checks=*")
+set(CMAKE_CXX_CLANG_TIDY clang-tidy;-header-filter=.;-checks=*;)
+
+file(GLOB_RECURSE SOURCES src/*.cpp)
+file(GLOB_RECURSE HEADERS src/*.h)
+file(GLOB_RECURSE TESTS test/*.cpp)
+
+set(LIB_PATH "${CMAKE_SOURCE_DIR}/../library")
+
+include_directories(${LIB_PATH}/include)
 add_executable(GUI ${SOURCES} ${HEADERS} main/main.cpp)
 
+target_link_libraries(GUI ${LIB_PATH}/lib/liblibrary.a)
+
 set(FLTK_SKIP_FLUID true)
 find_package(FLTK REQUIRED)
 include_directories(${FLTK_INCLUDE_DIR})
 target_link_libraries(${PROJECT_NAME} ${FLTK_BASE_LIBRARY} ${FLTK_PLATFORM_DEPENDENT_LIBS})
 
+enable_testing()
+find_package(Catch2 REQUIRED)
+add_executable(UnitTests ${SOURCES} ${HEADERS} ${TESTS})
+target_link_libraries(UnitTests Catch2::Catch2)
+
+include(CTest)
+include(Catch)
+catch_discover_tests(UnitTests)