Add poseidon-lengths test

poseidon-lengths/go/length_test.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"encoding/hex"
+	"fmt"
+	"testing"
+
+	"github.com/iden3/go-iden3-crypto/poseidon"
+)
+
+func TestLen(t *testing.T) {
+	m := []byte("45")
+	h, err := poseidon.HashBytes(m)
+	if err != nil {
+		t.Fatal(err)
+	}
+	fmt.Println("bigint", h.String())
+	fmt.Println("length", len(h.Bytes()))
+	fmt.Println("bytes", h.Bytes())
+	fmt.Println("hex", hex.EncodeToString(h.Bytes()))
+	if len(h.Bytes()) != 31 {
+		t.Fatal("expected 31 bytes")
+	}
+
+}