diff --git a/src/gamelib/grid_raytrace.cpp b/src/gamelib/grid_raytrace.cpp
index 5fd8519..862e0db 100644
--- a/src/gamelib/grid_raytrace.cpp
+++ b/src/gamelib/grid_raytrace.cpp
@@ -30,7 +30,9 @@
 #include <algorithm>
 
 namespace curry {
+#if !defined(BUILD_TESTING)
 	namespace {
+#endif
 		float inv_length (const vec2f& parVec) {
 			return 1.0f / std::sqrt(parVec.x() * parVec.x() + parVec.y() * parVec.y());
 		}
@@ -77,7 +79,9 @@ namespace curry {
 			//else
 				//return INFINITY;
 		}
+#if !defined(BUILD_TESTING)
 	} //unnamed namespace
+#endif
 
 	//see:
 	//http://stackoverflow.com/questions/24679963/precise-subpixel-line-drawing-algorithm-rasterization-algorithm
diff --git a/src/gamelib/grid_raytrace.hpp b/src/gamelib/grid_raytrace.hpp
index f3ab590..80b7123 100644
--- a/src/gamelib/grid_raytrace.hpp
+++ b/src/gamelib/grid_raytrace.hpp
@@ -20,12 +20,17 @@
 #pragma once
 
 #include "vector.hpp"
+#include "mycurry_toplevelConfig.h"
 #include <functional>
 
 namespace curry {
 	class WorldGrid;
 	class TileProperty;
 
+#if defined(BUILD_TESTING)
+	float segment_intersection (const vec2f& parA, const vec2f& parDirA, const vec2f& parB, const vec2f& parDirB);
+#endif
+
 	struct WorldTileProperty {
 		vec2us index;
 		const TileProperty* property;
diff --git a/src/mycurry_toplevelConfig.h.in b/src/mycurry_toplevelConfig.h.in
index 165dab5..ac6f3c4 100644
--- a/src/mycurry_toplevelConfig.h.in
+++ b/src/mycurry_toplevelConfig.h.in
@@ -20,3 +20,4 @@
 #pragma once
 
 #define RESOURCES_PATH "@MYCURRY_RESOURCES_PATH@/"
+#cmakedefine BUILD_TESTING
diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index 4134d13..4e3d6bf 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -17,6 +17,7 @@ target_include_directories(${PROJECT_NAME}
 	PRIVATE ${CMAKE_SOURCE_DIR}/src/gamelib
 	PRIVATE ${CMAKE_SOURCE_DIR}/lib/vectorwrapper/include
 	PRIVATE ${CMAKE_SOURCE_DIR}/lib/tree-2.81/src
+	PRIVATE ${CMAKE_BINARY_DIR}
 )
 
 add_test(