diff --git a/unittests/string_size.chai b/unittests/string_size.chai
new file mode 100644
index 0000000..94b32d5
--- /dev/null
+++ b/unittests/string_size.chai
@@ -0,0 +1,2 @@
+assert_equal(true, "".empty())
+assert_equal(3, "123".size())