add tests.

assets/CMakeLists.txt

@@ -3,7 +3,7 @@
 # This software is released under the MIT License.
 # https://opensource.org/licenses/MIT
 
-set(DUSK_GAME_ASSETS_DIR "${CMAKE_CURRENT_SOURCE_DIR}" CACHE INTERNAL ${DUSK_CACHE_TARGET})
+set(DUSK_GAME_ASSETS_DIR "${CMAKE_CURRENT_SOURCE_DIR}" CACHE INTERNAL "Game assets directory")
 
 # Palette asset needs to be added before any images.
 add_subdirectory(palette)