fix(build): add NBYTES_ENABLE_TESTING CMake option (#15)

To control whether to download test dependencies.

Author: GunniBusch

CMakeLists.txt

@@ -12,18 +12,26 @@ option(NBYTES_DEVELOPMENT_CHECKS "Enable development checks" OFF)
 
 include(GNUInstallDirs)
 include(FetchContent)
+include(CTest)
+
+option(NBYTES_ENABLE_TESTING "Enable testing" ${BUILD_TESTING})
 
-FetchContent_Declare(
-  googletest
-  URL https://github.com/google/googletest/archive/03597a01ee50ed33e9dfd640b249b4be3799d395.zip
-)
-# For Windows: Prevent overriding the parent project's compiler/linker settings
-set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
-FetchContent_MakeAvailable(googletest)
 
 add_subdirectory(src)
-enable_testing()
-add_subdirectory(tests)
+
+if (NBYTES_ENABLE_TESTING)
+  FetchContent_Declare(
+    googletest
+    URL https://github.com/google/googletest/archive/03597a01ee50ed33e9dfd640b249b4be3799d395.zip
+    URL_HASH SHA256=edd885a1ab32b6999515a880f669efadb80b3f880215f315985fa3f6eca7c4d3
+    FIND_PACKAGE_ARGS NAMES GTest
+  )
+  # For Windows: Prevent overriding the parent project's compiler/linker settings
+  set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+  FetchContent_MakeAvailable(googletest)
+
+  add_subdirectory(tests)
+endif()
 
 install(
   FILES include/nbytes.h