Implement findstring
diff --git a/test/findstring.mk b/test/findstring.mk
new file mode 100644
index 0000000..5f53ad9
--- /dev/null
+++ b/test/findstring.mk
@@ -0,0 +1,6 @@
+test:
+	echo $(findstring a, a b c)
+	echo $(findstring b, a b c)
+	echo $(findstring b c, a b c)
+	echo $(findstring a, b c)
+	echo $(findstring a, b c, a)