initial changes

cmake/libraries/testing.cmake

@@ -0,0 +1,17 @@
+if (PROJECT_ENABLE_TESTING)
+  if(PROJECT_BUILD)
+    add_definitions(-DPROJECT_ENABLE_TESTING)
+  elseif(NOT PROJECT_IS_MINGW)
+    ExternalProject_Add(gtest_project
+      PREFIX external
+      URL ${PROJECT_3RD_PARTY_DIR}/googletest-${GTEST_VERSION}.tar.gz
+      URL_HASH SHA256=${GTEST_HASH}
+      LIST_SEPARATOR |
+      CMAKE_ARGS ${PROJECT_EXTERNAL_CMAKE_FLAGS}
+        -DBUILD_SHARED_LIBS=${PROJECT_BUILD_SHARED_LIBS}
+        -DBUILD_STATIC_LIBS=ON
+    )
+
+    list(APPEND PROJECT_DEPENDENCIES gtest_project)
+  endif()
+endif()