[#525] event/container: Parse session token from SetEACL notification

The 4th item of `SetEACL` container notification event is a byte array of
serialized session token.

Parse session token in `ParseSetEACL` function. Provide
`SetEACL.SessionToken` method.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/morph/event/container/eacl.go

@@ -16,6 +16,8 @@ type SetEACL struct {
 	signature []byte
 
 	publicKey []byte
+
+	token []byte
 }
 
 // MorphEvent implements Neo:Morph Event interface.
@@ -37,6 +39,12 @@ func (x SetEACL) PublicKey() []byte {
 	return x.publicKey
 }
 
+// Session token returns binary token of the session
+// within which the eACL was set.
+func (x SetEACL) SessionToken() []byte {
+	return x.token
+}
+
 // ParseSetEACL parses SetEACL notification event from list of stack items.
 //
 // Expects 4 stack items.
@@ -70,5 +78,11 @@ func ParseSetEACL(items []stackitem.Item) (event.Event, error) {
 		return nil, fmt.Errorf("could not parse binary public key: %w", err)
 	}
 
+	// parse session token
+	ev.token, err = client.BytesFromStackItem(items[3])
+	if err != nil {
+		return nil, fmt.Errorf("could not get sesison token: %w", err)
+	}
+
 	return ev, nil
 }

pkg/morph/event/container/eacl_test.go

@@ -14,6 +14,7 @@ func TestParseEACL(t *testing.T) {
 		binaryTable = []byte("table")
 		signature   = []byte("signature")
 		publicKey   = []byte("pubkey")
+		token       = []byte("token")
 	)
 
 	t.Run("wrong number of parameters", func(t *testing.T) {
@@ -55,12 +56,23 @@ func TestParseEACL(t *testing.T) {
 		require.Error(t, err)
 	})
 
+	t.Run("wrong session token parameter", func(t *testing.T) {
+		_, err := container.ParseSetEACL([]stackitem.Item{
+			stackitem.NewByteArray(binaryTable),
+			stackitem.NewByteArray(signature),
+			stackitem.NewByteArray(publicKey),
+			stackitem.NewMap(),
+		})
+
+		require.Error(t, err)
+	})
+
 	t.Run("correct behavior", func(t *testing.T) {
 		ev, err := container.ParseSetEACL([]stackitem.Item{
 			stackitem.NewByteArray(binaryTable),
 			stackitem.NewByteArray(signature),
 			stackitem.NewByteArray(publicKey),
-			stackitem.NewMap(),
+			stackitem.NewByteArray(token),
 		})
 		require.NoError(t, err)
 
@@ -69,5 +81,6 @@ func TestParseEACL(t *testing.T) {
 		require.Equal(t, binaryTable, e.Table())
 		require.Equal(t, signature, e.Signature())
 		require.Equal(t, publicKey, e.PublicKey())
+		require.Equal(t, token, e.SessionToken())
 	})
 }