add a test

hello/moarstrings/reverse_test.go

@@ -0,0 +1,19 @@
+package moarstrings
+
+import "testing"
+
+func TestReverseRunes(t *testing.T) {
+	cases := []struct {
+		in, want string
+	}{
+		{"Hello, world", "dlrow ,olleH"},
+		{"Hello, 世界", "界世 ,olleH"},
+		{"", ""},
+	}
+	for _, c := range cases {
+		got := ReverseRunes(c.in)
+		if got != c.want {
+			t.Errorf("ReverseRunes(%q) == %q, want %q", c.in, got, c.want)
+		}
+	}
+}