remove "current" from receiver, add very simple serialization test

elkrem/elkrem.go

@@ -104,9 +104,13 @@ func NewElkremReceiver(th uint8) ElkremReceiver {
 
 // Next() increments the index to the next hash and outputs it
 func (e *ElkremSender) Next() (*wire.ShaHash, error) {
-	// increment index
+	sha, err := e.AtIndex(e.current)
+	if err != nil {
+		return nil, err
+	}
+	// increment index for next time
 	e.current++
-	return e.AtIndex(e.current)
+	return sha, nil
 }
 
 // w is the wanted index, i is the root index

elkrem/elkrem_test.go

@@ -8,10 +8,11 @@ import (
 
 // TestElkremBig makes a height 63 (max size possible) tree and tries 10K hashes
 func TestElkremBig(t *testing.T) {
-	ex := NewElkremSender(63, wire.DoubleSha256SH([]byte("elktest")))
+	sndr := NewElkremSender(63, wire.DoubleSha256SH([]byte("elktest")))
 	rcv := NewElkremReceiver(63)
+	SenderSerdesTest(t, sndr)
 	for n := uint64(0); n < 10000; n++ {
-		sha, err := ex.AtIndex(n)
+		sha, err := sndr.Next()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -27,22 +28,23 @@ func TestElkremBig(t *testing.T) {
 			}
 		}
 	}
+	SenderSerdesTest(t, sndr)
+	ReceiverSerdesTest(t, rcv)
 	for n := uint64(0); n < 10000; n += 500 {
 		sha, err := rcv.AtIndex(n)
 		if err != nil {
 			t.Fatal(err)
 		}
-		t.Logf("Retreived index %d %s\n",
-			n, sha.String())
+		t.Logf("Retreived index %d %s\n", n, sha.String())
 	}
 }
 
 // TestElkremSmall makes a height 15 (65534 size) tree and tries 10K hashes
 func TestElkremSmall(t *testing.T) {
-	ex := NewElkremSender(15, wire.DoubleSha256SH([]byte("elktest")))
+	sndr := NewElkremSender(15, wire.DoubleSha256SH([]byte("elktest")))
 	rcv := NewElkremReceiver(15)
 	for n := uint64(0); n < 5000; n++ {
-		sha, err := ex.AtIndex(n)
+		sha, err := sndr.Next()
 		if err != nil {
 			t.Fatal(err)
 		}

elkrem/serdes.go

@@ -38,7 +38,7 @@ func (e *ElkremSender) ToBytes() ([]byte, error) {
 		return nil, fmt.Errorf("%d byte hash, expect 32", n)
 	}
 
-	return nil, nil
+	return buf.Bytes(), nil
 }
 
 // ElkremSenderFromBytes turns a 41 byte slice into a sender, picking up at

elkrem/serdes_test.go

@@ -0,0 +1,19 @@
+package elkrem
+
+import "testing"
+
+func ReceiverSerdesTest(t *testing.T, er ElkremReceiver) {
+	b, err := er.ToBytes()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Serialized receiver; %d bytes, hex:\n%x\n", len(b), b)
+}
+
+func SenderSerdesTest(t *testing.T, es ElkremSender) {
+	b, err := es.ToBytes()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Serialized sender; %d bytes, hex:\n%x\n", len(b), b)
+}