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

The 3rd item of `Delete` container notification event is a byte array of
serialized session token.  Parse session token in `ParseDelete` function.
Provide `Delete.SessionToken` method.

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

pkg/morph/event/container/delete.go

@@ -12,6 +12,7 @@ import (
 type Delete struct {
 	containerID []byte
 	signature   []byte
+	token       []byte
 }
 
 // MorphEvent implements Neo:Morph Event interface.
@@ -23,15 +24,25 @@ func (d Delete) ContainerID() []byte { return d.containerID }
 // Signature of marshalled container by container owner.
 func (d Delete) Signature() []byte { return d.signature }
 
+// SessionToken returns binary token of the session
+// within which the eACL was set.
+func (d Delete) SessionToken() []byte {
+	return d.token
+}
+
 // ParseDelete from notification into container event structure.
+//
+// Expects 3 stack items.
 func ParseDelete(params []stackitem.Item) (event.Event, error) {
 	var (
 		ev  Delete
 		err error
 	)
 
-	if ln := len(params); ln != 2 {
+	const expectedItemNumEACL = 3
-		return nil, event.WrongNumberOfParameters(2, ln)
+
+	if ln := len(params); ln != expectedItemNumEACL {
+		return nil, event.WrongNumberOfParameters(expectedItemNumEACL, ln)
 	}
 
 	// parse container
@@ -46,5 +57,11 @@ func ParseDelete(params []stackitem.Item) (event.Event, error) {
 		return nil, fmt.Errorf("could not get signature: %w", err)
 	}
 
+	// parse session token
+	ev.token, err = client.BytesFromStackItem(params[2])
+	if err != nil {
+		return nil, fmt.Errorf("could not get session token: %w", err)
+	}
+
 	return ev, nil
 }

pkg/morph/event/container/delete_test.go

@@ -12,6 +12,7 @@ func TestParseDelete(t *testing.T) {
 	var (
 		containerID = []byte("containreID")
 		signature   = []byte("signature")
+		token       = []byte("token")
 	)
 
 	t.Run("wrong number of parameters", func(t *testing.T) {
@@ -20,7 +21,7 @@ func TestParseDelete(t *testing.T) {
 		}
 
 		_, err := ParseDelete(prms)
-		require.EqualError(t, err, event.WrongNumberOfParameters(2, len(prms)).Error())
+		require.EqualError(t, err, event.WrongNumberOfParameters(3, len(prms)).Error())
 	})
 
 	t.Run("wrong container parameter", func(t *testing.T) {
@@ -40,10 +41,21 @@ func TestParseDelete(t *testing.T) {
 		require.Error(t, err)
 	})
 
+	t.Run("wrong session token parameter", func(t *testing.T) {
+		_, err := ParseDelete([]stackitem.Item{
+			stackitem.NewByteArray(containerID),
+			stackitem.NewByteArray(signature),
+			stackitem.NewMap(),
+		})
+
+		require.Error(t, err)
+	})
+
 	t.Run("correct behavior", func(t *testing.T) {
 		ev, err := ParseDelete([]stackitem.Item{
 			stackitem.NewByteArray(containerID),
 			stackitem.NewByteArray(signature),
+			stackitem.NewByteArray(token),
 		})
 
 		require.NoError(t, err)
@@ -51,6 +63,7 @@ func TestParseDelete(t *testing.T) {
 		require.Equal(t, Delete{
 			containerID: containerID,
 			signature:   signature,
+			token:       token,
 		}, ev)
 	})
 }