Interface compatibility with *tls.Conn

In order to use struct embedding and reduce boilerplate for functions
that take interfaces that return tls.ConnectionState, use the same
interface as the net/tls package.

connection.go

@@ -235,8 +235,10 @@ func (me *Connection) LocalAddr() net.Addr {
 	return &net.TCPAddr{}
 }
 
-// TLSConnectionState returns basic TLS details of the underlying transport.
-func (me *Connection) TLSConnectionState() tls.ConnectionState {
+// ConnectionState returns basic TLS details of the underlying transport.
+// Returns a zero value when the underlying connection does not implement
+// ConnectionState() tls.ConnectionState.
+func (me *Connection) ConnectionState() tls.ConnectionState {
 	if c, ok := me.conn.(interface {
 		ConnectionState() tls.ConnectionState
 	}); ok {

tls_test.go

@@ -4,11 +4,12 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"fmt"
-	"github.com/streadway/amqp"
 	"io"
 	"net"
 	"testing"
 	"time"
+
+	"github.com/streadway/amqp"
 )
 
 type tlsServer struct {
@@ -94,8 +95,7 @@ func TestTLSHandshake(t *testing.T) {
 		}
 	}
 
-	st := c.TLSConnectionState()
-	if !st.HandshakeComplete {
+	if st := c.ConnectionState(); !st.HandshakeComplete {
 		t.Errorf("TLS handshake failed, TLS connection state: %+v", st)
 	}
 }