Move FromBytes/ToBytes test into ed25519_test.go.

The two other tests weren't actually testing anything more than this one
and, with them gone, we didn't need a separate file for single remaining
test.

ed25519_test.go

@@ -8,11 +8,14 @@ import (
 	"bufio"
 	"bytes"
 	"compress/gzip"
+	"crypto/rand"
 	"encoding/hex"
 	"io"
 	"os"
 	"strings"
 	"testing"
+
+	"github.com/agl/ed25519/edwards25519"
 )
 
 type zeroReader struct{}
@@ -24,6 +27,22 @@ func (zeroReader) Read(buf []byte) (int, error) {
 	return len(buf), nil
 }
 
+func TestUnmarshalMarshal(t *testing.T) {
+	pub, _, _ := GenerateKey(rand.Reader)
+
+	var A edwards25519.ExtendedGroupElement
+	if !A.FromBytes(pub) {
+		t.Fatalf("ExtendedGroupElement.FromBytes failed")
+	}
+
+	var pub2 [32]byte
+	A.ToBytes(&pub2)
+
+	if *pub != pub2 {
+		t.Errorf("FromBytes(%v)->ToBytes does not round-trip, got %x\n", *pub, pub2)
+	}
+}
+
 func TestSignVerify(t *testing.T) {
 	var zero zeroReader
 	public, private, _ := GenerateKey(zero)