cmake: add_dependencies must have at least 2 arguments

test/CMakeLists.txt

@@ -128,7 +128,9 @@ macro(add_sdl_test_executable TARGET)
         set_property(TARGET ${TARGET} PROPERTY C_STANDARD 90)
         set_property(TARGET ${TARGET} PROPERTY C_EXTENSIONS FALSE)
     endif()
-    add_dependencies(${TARGET} ${AST_DEPENDS})
+    if(AST_DEPENDS)
+        add_dependencies(${TARGET} ${AST_DEPENDS})
+    endif()
 
     list(APPEND SDL_TEST_EXECUTABLES ${TARGET})
     set_property(TARGET ${TARGET} PROPERTY SDL_NOTRACKMEM ${AST_NOTRACKMEM})