Add tests for socket expr

Signed-off-by: black-desk <me@black-desk.cn>

expr/socket_test.go

@@ -0,0 +1,86 @@
+package expr
+
+import (
+	"encoding/binary"
+	"reflect"
+	"testing"
+
+	"github.com/mdlayher/netlink"
+	"golang.org/x/sys/unix"
+)
+
+func TestSocket(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name   string
+		socket Socket
+	}{
+		{
+			name: "Unmarshal `socket transparent`",
+			socket: Socket{
+				Key:      SocketKeyTransparent,
+				Level:    0,
+				Register: 1,
+			},
+		},
+		{
+			name: "Unmarshal `socket cgroup level 5`",
+			socket: Socket{
+				Key:      SocketKeyCgroupv2,
+				Level:    5,
+				Register: 1,
+			},
+		},
+		{
+			name: "Unmarshal `socket cgroup level 1`",
+			socket: Socket{
+				Key:      SocketKeyCgroupv2,
+				Level:    1,
+				Register: 1,
+			},
+		},
+		{
+			name: "Unmarshal `socket wildcard`",
+			socket: Socket{
+				Key:      SocketKeyWildcard,
+				Level:    0,
+				Register: 1,
+			},
+		},
+		{
+			name: "Unmarshal `socket mark`",
+			socket: Socket{
+				Key:      SocketKeyMark,
+				Level:    0,
+				Register: 1,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			nSocket := Socket{}
+			data, err := tt.socket.marshal(0 /* don't care in this test */)
+			if err != nil {
+				t.Fatalf("marshal error: %+v", err)
+
+			}
+			ad, err := netlink.NewAttributeDecoder(data)
+			if err != nil {
+				t.Fatalf("NewAttributeDecoder() error: %+v", err)
+			}
+			ad.ByteOrder = binary.BigEndian
+			for ad.Next() {
+				if ad.Type() == unix.NFTA_EXPR_DATA {
+					if err := nSocket.unmarshal(0, ad.Bytes()); err != nil {
+						t.Errorf("unmarshal error: %+v", err)
+						break
+					}
+				}
+			}
+			if !reflect.DeepEqual(tt.socket, nSocket) {
+				t.Fatalf("original %+v and recovered %+v Socket structs are different", tt.socket, nSocket)
+			}
+		})
+	}
+}