add unit tests

Makefile

@@ -1,4 +1,4 @@
-.PHONY: shaders-vulkan shaders-d3d12 shaders-metal shaders-all toad check help
+.PHONY: shaders-vulkan shaders-d3d12 shaders-metal shaders-all toad check test help
 
 help:
 	@echo "Targets:"
@@ -6,6 +6,7 @@ help:
 	@echo "  shaders-d3d12   Compile DXIL into shaders/d3d12/ (needs shadercross)"
 	@echo "  shaders-metal   Compile MSL into shaders/metal/ (needs shadercross)"
 	@echo "  shaders-all     Build all shader backends"
+	@echo "  test            Run engine pure unit tests"
 	@echo "  check           Typecheck examples/toad"
 	@echo "  toad            Run the toad example"
 
@@ -20,6 +21,9 @@ shaders-metal:
 
 shaders-all: shaders-vulkan shaders-d3d12 shaders-metal
 
+test:
+	odin test engine
+
 check:
 	odin check examples/toad -collection:pkg=.