mock adapter: Group all replies for one request under one call to MockReply

Sequence numbers are now used to match requests with replies.
Mock adapter thus has to be able to tell how many messages
from the head of the queue with mock replies belong to the currently
processed request. Then they can be given the right context and
the rest of the queued replies are postponed to be delivered later
(when context of their request is known).

All replies for one request are now therefore queued together.
This affects just multipart requests for which replies have to
be pushed all at once. The trailling control ping reply is still
queued separately, however, because that is actualy another request,
e.g.:

    mockVpp.MockReply(  // push multipart messages all at once
                      &interfaces.SwInterfaceDetails{SwIfIndex:1},
                      &interfaces.SwInterfaceDetails{SwIfIndex:2},
                      &interfaces.SwInterfaceDetails{SwIfIndex:3},
    )
    mockVpp.MockReply(&vpe.ControlPingReply{})

Even if the multipart request has no replies, MockReply has to be
called exactly twice:

    mockVpp.MockReply()  // zero multipart messages
    mockVpp.MockReply(&vpe.ControlPingReply{})

Change-Id: I28c15d2f52d14dca0b7fb06033d7270a7da2bde6
Signed-off-by: Milan Lenco <milan.lenco@pantheon.tech>

4 files changed, 222 insertions, 122 deletions

diff --git a/adapter/mock/mock_adapter.go b/adapter/mock/mock_adapter.go
index ae4caf0..959fd86 100644
--- a/adapter/mock/mock_adapter.go
+++ b/adapter/mock/mock_adapter.go
@@ -67,11 +67,19 @@ type MessageDTO struct {
 	Data     []byte
 }
 
+// reply for one request (can be multipart, contain replies to previously timeouted requests, etc.)
 type reply struct {
-	msg       api.Message
-	multipart bool
-	hasSeqNum bool
-	seqNum    uint16
+	msgs []MsgWithContext
+}
+
+// MsgWithContext encapsulates reply message with possibly sequence number and is-multipart flag.
+type MsgWithContext struct {
+	Msg       api.Message
+	SeqNum    uint16
+	Multipart bool
+
+	/* set by mock adapter */
+	hasCtx    bool
 }
 
 // ReplyHandler is a type that allows to extend the behaviour of VPP mock.
@@ -253,37 +261,32 @@ func (a *VppAdapter) SendMsg(clientID uint32, data []byte) error {
 		a.repliesLock.Lock()
 		defer a.repliesLock.Unlock()
 
-		// pop all replies from queue
-		withSeqNums := false
-		for i, reply := range a.replies {
-			if i > 0 && reply.msg.GetMessageName() == "control_ping_reply" && !withSeqNums {
-				// hack - do not send control_ping_reply immediately, leave it for the the next callback
-				a.replies = a.replies[i:]
-				return nil
-			}
-			msgID, _ := a.GetMsgID(reply.msg.GetMessageName(), reply.msg.GetCrcString())
-			buf := new(bytes.Buffer)
-			context := clientID
-			context = setMultipart(context, reply.multipart)
-			if reply.hasSeqNum {
-				withSeqNums = true
-				context = setSeqNum(context, reply.seqNum)
-			}
-			if reply.msg.GetMessageType() == api.ReplyMessage {
-				struc.Pack(buf, &core.VppReplyHeader{VlMsgID: msgID, Context: context})
-			} else if reply.msg.GetMessageType() == api.EventMessage {
-				struc.Pack(buf, &core.VppEventHeader{VlMsgID: msgID, Context: context})
-			} else if reply.msg.GetMessageType() == api.RequestMessage {
-				struc.Pack(buf, &core.VppRequestHeader{VlMsgID: msgID, Context: context})
-			} else {
-				struc.Pack(buf, &core.VppOtherHeader{VlMsgID: msgID})
-			}
-			struc.Pack(buf, reply.msg)
-			a.callback(context, msgID, buf.Bytes())
-		}
+		// pop the first reply
 		if len(a.replies) > 0 {
-			a.replies = []reply{}
-			if len(a.replyHandlers) > 0 {
+			reply := a.replies[0]
+			for _, msg := range reply.msgs {
+				msgID, _ := a.GetMsgID(msg.Msg.GetMessageName(), msg.Msg.GetCrcString())
+				buf := new(bytes.Buffer)
+				context := clientID
+				if msg.hasCtx {
+					context = setMultipart(context, msg.Multipart)
+					context = setSeqNum(context, msg.SeqNum)
+				}
+				if msg.Msg.GetMessageType() == api.ReplyMessage {
+					struc.Pack(buf, &core.VppReplyHeader{VlMsgID: msgID, Context: context})
+				} else if msg.Msg.GetMessageType() == api.EventMessage {
+					struc.Pack(buf, &core.VppEventHeader{VlMsgID: msgID, Context: context})
+				} else if msg.Msg.GetMessageType() == api.RequestMessage {
+					struc.Pack(buf, &core.VppRequestHeader{VlMsgID: msgID, Context: context})
+				} else {
+					struc.Pack(buf, &core.VppOtherHeader{VlMsgID: msgID})
+				}
+				struc.Pack(buf, msg.Msg)
+				a.callback(context, msgID, buf.Bytes())
+			}
+
+			a.replies = a.replies[1:]
+			if len(a.replies) == 0 && len(a.replyHandlers) > 0 {
 				// Switch back to handlers once the queue is empty to revert back
 				// the fallthrough effect.
 				a.mode = useReplyHandlers
@@ -313,24 +316,56 @@ func (a *VppAdapter) WaitReady() error {
 	return nil
 }
 
-// MockReply stores a message to be returned when the next request comes. It is a FIFO queue - multiple replies
-// can be pushed into it, the first one will be popped when some request comes.
-// Using of this method automatically switches the mock into th useRepliesQueue mode.
-func (a *VppAdapter) MockReply(replyMsg api.Message, isMultipart bool) {
+// MockReply stores a message or a list of multipart messages to be returned when
+// the next request comes. It is a FIFO queue - multiple replies can be pushed into it,
+// the first message or the first set of multi-part messages will be popped when
+// some request comes.
+// Using of this method automatically switches the mock into the useRepliesQueue mode.
+//
+// Note: multipart requests are implemented using two requests actually - the multipart
+// request itself followed by control ping used to tell which multipart message
+// is the last one. A mock reply to a multipart request has to thus consist of
+// exactly two calls of this method.
+// For example:
+//
+//    mockVpp.MockReply(  // push multipart messages all at once
+// 			&interfaces.SwInterfaceDetails{SwIfIndex:1},
+// 			&interfaces.SwInterfaceDetails{SwIfIndex:2},
+// 			&interfaces.SwInterfaceDetails{SwIfIndex:3},
+//    )
+//    mockVpp.MockReply(&vpe.ControlPingReply{})
+//
+// Even if the multipart request has no replies, MockReply has to be called twice:
+//
+//    mockVpp.MockReply()  // zero multipart messages
+//    mockVpp.MockReply(&vpe.ControlPingReply{})
+func (a *VppAdapter) MockReply(msgs ...api.Message) {
 	a.repliesLock.Lock()
 	defer a.repliesLock.Unlock()
 
-	a.replies = append(a.replies, reply{msg: replyMsg, multipart: isMultipart, hasSeqNum: false})
+	r := reply{}
+	for _, msg := range msgs {
+		r.msgs = append(r.msgs, MsgWithContext{Msg: msg, hasCtx: false})
+	}
+	a.replies = append(a.replies, r)
 	a.mode = useRepliesQueue
 }
 
-// MockReplyWithSeqNum queues next reply like MockReply() does, except that the
-// sequence number can be customized and not necessarily match with the request.
-func (a *VppAdapter) MockReplyWithSeqNum(replyMsg api.Message, isMultipart bool, sequenceNum uint16) {
+// MockReplyWithContext queues next reply like MockReply() does, except that the
+// sequence number and multipart flag (= context minus channel ID) can be customized
+// and not necessarily match with the request.
+// The purpose of this function is to test handling of sequence numbers and as such
+// it is not really meant to be used outside the govpp UTs.
+func (a *VppAdapter) MockReplyWithContext(msgs ...MsgWithContext) {
 	a.repliesLock.Lock()
 	defer a.repliesLock.Unlock()
 
-	a.replies = append(a.replies, reply{msg: replyMsg, multipart: isMultipart, hasSeqNum: true, seqNum: sequenceNum})
+	r := reply{}
+	for _, msg := range msgs {
+		r.msgs = append(r.msgs,
+			MsgWithContext{Msg: msg.Msg, SeqNum: msg.SeqNum, Multipart: msg.Multipart, hasCtx: true})
+	}
+	a.replies = append(a.replies, r)
 	a.mode = useRepliesQueue
 }
 
diff --git a/api/api.go b/api/api.go
index 3c2c7ec..34e17c1 100644
--- a/api/api.go
+++ b/api/api.go
@@ -87,7 +87,7 @@ type MessageIdentifier interface {
 // methods  provided inside of this package. Do not use the same channel from multiple goroutines concurrently,
 // otherwise the responses could mix! Use multiple channels instead.
 type Channel struct {
-	ID        uint16 // channel ID
+	ID uint16 // channel ID
 
 	ReqChan   chan *VppRequest // channel for sending the requests to VPP, closing this channel releases all resources in the ChannelProvider
 	ReplyChan chan *VppReply   // channel where VPP replies are delivered to
@@ -134,13 +134,13 @@ type NotifSubscription struct {
 
 // RequestCtx is a context of a ongoing request (simple one - only one response is expected).
 type RequestCtx struct {
-	ch *Channel
+	ch     *Channel
 	seqNum uint16
 }
 
 // MultiRequestCtx is a context of a ongoing multipart request (multiple responses are expected).
 type MultiRequestCtx struct {
-	ch *Channel
+	ch     *Channel
 	seqNum uint16
 }
 
@@ -151,7 +151,7 @@ const defaultReplyTimeout = time.Second * 1 // default timeout for replies from
 // Use ChannelProvider to get an API channel ready for communication with VPP.
 func NewChannelInternal(id uint16) *Channel {
 	return &Channel{
-		ID: id,
+		ID:           id,
 		replyTimeout: defaultReplyTimeout,
 	}
 }
@@ -175,7 +175,7 @@ func (ch *Channel) SendRequest(msg Message) *RequestCtx {
 	ch.lastSeqNum++
 	ch.ReqChan <- &VppRequest{
 		Message: msg,
-		SeqNum: ch.lastSeqNum,
+		SeqNum:  ch.lastSeqNum,
 	}
 	return &RequestCtx{ch: ch, seqNum: ch.lastSeqNum}
 }
@@ -266,7 +266,7 @@ func (ch *Channel) processReply(reply *VppReply, expSeqNum uint16, msg Message)
 		ignore = true
 		return
 	}
-	if cmpSeqNums == 1  {
+	if cmpSeqNums == 1 {
 		ch.delayedReply = reply
 		err = fmt.Errorf("missing binary API reply with sequence number: %d", expSeqNum)
 		return
@@ -298,8 +298,8 @@ func (ch *Channel) processReply(reply *VppReply, expSeqNum uint16, msg Message)
 			msgNameCrc = nameCrc
 		}
 
-		err = fmt.Errorf("received invalid message ID (seq-num=%d), expected %d (%s), but got %d (%s) " +
-		"(check if multiple goroutines are not sharing single GoVPP channel)",
+		err = fmt.Errorf("received invalid message ID (seq-num=%d), expected %d (%s), but got %d (%s) "+
+			"(check if multiple goroutines are not sharing single GoVPP channel)",
 			reply.SeqNum, expMsgID, msg.GetMessageName(), reply.MessageID, msgNameCrc)
 		return
 	}
diff --git a/api/api_test.go b/api/api_test.go
index a83b1cc..7cbd9f0 100644
--- a/api/api_test.go
+++ b/api/api_test.go
@@ -64,7 +64,7 @@ func TestRequestReplyTapConnect(t *testing.T) {
 	ctx.mockVpp.MockReply(&tap.TapConnectReply{
 		Retval:    10,
 		SwIfIndex: 1,
-	}, false)
+	})
 	request := &tap.TapConnect{
 		TapName:      []byte("test-tap-name"),
 		UseRandomMac: 1,
@@ -84,7 +84,7 @@ func TestRequestReplyTapModify(t *testing.T) {
 	ctx.mockVpp.MockReply(&tap.TapModifyReply{
 		Retval:    15,
 		SwIfIndex: 2,
-	}, false)
+	})
 	request := &tap.TapModify{
 		TapName:           []byte("test-tap-modify"),
 		UseRandomMac:      1,
@@ -104,7 +104,7 @@ func TestRequestReplyTapDelete(t *testing.T) {
 
 	ctx.mockVpp.MockReply(&tap.TapDeleteReply{
 		Retval: 20,
-	}, false)
+	})
 	request := &tap.TapDelete{
 		SwIfIndex: 3,
 	}
@@ -123,7 +123,7 @@ func TestRequestReplySwInterfaceTapDump(t *testing.T) {
 	ctx.mockVpp.MockReply(&tap.SwInterfaceTapDetails{
 		SwIfIndex: 25,
 		DevName:   byteName,
-	}, false)
+	})
 	request := &tap.SwInterfaceTapDump{}
 	reply := &tap.SwInterfaceTapDetails{}
 
@@ -140,7 +140,7 @@ func TestRequestReplyMemifCreate(t *testing.T) {
 	ctx.mockVpp.MockReply(&memif.MemifCreateReply{
 		Retval:    22,
 		SwIfIndex: 4,
-	}, false)
+	})
 	request := &memif.MemifCreate{
 		Role:       10,
 		ID:         12,
@@ -161,7 +161,7 @@ func TestRequestReplyMemifDelete(t *testing.T) {
 
 	ctx.mockVpp.MockReply(&memif.MemifDeleteReply{
 		Retval: 24,
-	}, false)
+	})
 	request := &memif.MemifDelete{
 		SwIfIndex: 15,
 	}
@@ -180,7 +180,7 @@ func TestRequestReplyMemifDetails(t *testing.T) {
 		SwIfIndex: 25,
 		IfName:    []byte("memif-name"),
 		Role:      0,
-	}, false)
+	})
 	request := &memif.MemifDump{}
 	reply := &memif.MemifDetails{}
 
@@ -196,13 +196,15 @@ func TestMultiRequestReplySwInterfaceTapDump(t *testing.T) {
 	defer ctx.teardownTest()
 
 	// mock reply
+	msgs := []api.Message{}
 	for i := 1; i <= 10; i++ {
-		ctx.mockVpp.MockReply(&tap.SwInterfaceTapDetails{
+		msgs = append(msgs, &tap.SwInterfaceTapDetails{
 			SwIfIndex: uint32(i),
 			DevName:   []byte("dev-name-test"),
-		}, true)
+		})
 	}
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, true)
+	ctx.mockVpp.MockReply(msgs...)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 
 	reqCtx := ctx.ch.SendMultiRequest(&tap.SwInterfaceTapDump{})
 	cnt := 0
@@ -223,12 +225,14 @@ func TestMultiRequestReplySwInterfaceMemifDump(t *testing.T) {
 	defer ctx.teardownTest()
 
 	// mock reply
+	msgs := []api.Message{}
 	for i := 1; i <= 10; i++ {
-		ctx.mockVpp.MockReply(&memif.MemifDetails{
+		msgs = append(msgs, &memif.MemifDetails{
 			SwIfIndex: uint32(i),
-		}, true)
+		})
 	}
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, true)
+	ctx.mockVpp.MockReply(msgs...)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 
 	reqCtx := ctx.ch.SendMultiRequest(&memif.MemifDump{})
 	cnt := 0
@@ -257,7 +261,7 @@ func TestNotifications(t *testing.T) {
 	ctx.mockVpp.MockReply(&interfaces.SwInterfaceSetFlags{
 		SwIfIndex:   3,
 		AdminUpDown: 1,
-	}, false)
+	})
 	ctx.mockVpp.SendMsg(0, []byte(""))
 
 	// receive the notification
@@ -292,7 +296,7 @@ func TestNotificationEvent(t *testing.T) {
 	ctx.mockVpp.MockReply(&interfaces.SwInterfaceEvent{
 		SwIfIndex:  2,
 		LinkUpDown: 1,
-	}, false)
+	})
 	ctx.mockVpp.SendMsg(0, []byte(""))
 
 	// receive the notification
@@ -328,7 +332,7 @@ func TestSetReplyTimeout(t *testing.T) {
 	ctx.ch.SetReplyTimeout(time.Millisecond)
 
 	// first one request should work
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, false)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 	err := ctx.ch.SendRequest(&vpe.ControlPing{}).ReceiveReply(&vpe.ControlPingReply{})
 	Expect(err).ShouldNot(HaveOccurred())
 
@@ -344,13 +348,15 @@ func TestSetReplyTimeoutMultiRequest(t *testing.T) {
 
 	ctx.ch.SetReplyTimeout(time.Millisecond)
 
+	msgs := []api.Message{}
 	for i := 1; i <= 3; i++ {
-		ctx.mockVpp.MockReply(&interfaces.SwInterfaceDetails{
+		msgs = append(msgs, &interfaces.SwInterfaceDetails{
 			SwIfIndex:     uint32(i),
 			InterfaceName: []byte("if-name-test"),
-		}, true)
+		})
 	}
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, true)
+	ctx.mockVpp.MockReply(msgs...)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 
 	cnt := 0
 	sendMultiRequest := func() error {
@@ -409,20 +415,33 @@ func TestMultiRequestDouble(t *testing.T) {
 	defer ctx.teardownTest()
 
 	// mock reply
+	msgs := []mock.MsgWithContext{}
 	for i := 1; i <= 3; i++ {
-		ctx.mockVpp.MockReplyWithSeqNum(&interfaces.SwInterfaceDetails{
-			SwIfIndex:     uint32(i),
-			InterfaceName: []byte("if-name-test"),
-		}, true, 1)
+		msgs = append(msgs, mock.MsgWithContext{
+			Msg: &interfaces.SwInterfaceDetails{
+				SwIfIndex:     uint32(i),
+				InterfaceName: []byte("if-name-test"),
+			},
+			Multipart: true,
+			SeqNum:    1,
+		})
 	}
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{}, true, 1)
+	msgs = append(msgs, mock.MsgWithContext{Msg: &vpe.ControlPingReply{}, Multipart: true, SeqNum: 1})
+
 	for i := 1; i <= 3; i++ {
-		ctx.mockVpp.MockReplyWithSeqNum(&interfaces.SwInterfaceDetails{
-			SwIfIndex:     uint32(i),
-			InterfaceName: []byte("if-name-test"),
-		}, true, 2)
+		msgs = append(msgs,
+			mock.MsgWithContext{
+				Msg: &interfaces.SwInterfaceDetails{
+					SwIfIndex:     uint32(i),
+					InterfaceName: []byte("if-name-test"),
+				},
+				Multipart: true,
+				SeqNum:    2,
+			})
 	}
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{}, true,2)
+	msgs = append(msgs, mock.MsgWithContext{Msg: &vpe.ControlPingReply{}, Multipart: true, SeqNum: 2})
+
+	ctx.mockVpp.MockReplyWithContext(msgs...)
 
 	cnt := 0
 	var sendMultiRequest = func() error {
@@ -457,7 +476,7 @@ func TestReceiveReplyAfterTimeout(t *testing.T) {
 	ctx.ch.SetReplyTimeout(time.Millisecond)
 
 	// first one request should work
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{}, false,1)
+	ctx.mockVpp.MockReplyWithContext(mock.MsgWithContext{Msg: &vpe.ControlPingReply{}, SeqNum: 1})
 	err := ctx.ch.SendRequest(&vpe.ControlPing{}).ReceiveReply(&vpe.ControlPingReply{})
 	Expect(err).ShouldNot(HaveOccurred())
 
@@ -465,11 +484,11 @@ func TestReceiveReplyAfterTimeout(t *testing.T) {
 	Expect(err).Should(HaveOccurred())
 	Expect(err.Error()).To(ContainSubstring("timeout"))
 
-	// simulating late reply
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{}, false,2)
-
-	// normal reply for next request
-	ctx.mockVpp.MockReplyWithSeqNum(&tap.TapConnectReply{}, false,3)
+	ctx.mockVpp.MockReplyWithContext(
+		// simulating late reply
+		mock.MsgWithContext{Msg: &vpe.ControlPingReply{}, SeqNum: 2},
+		// normal reply for next request
+		mock.MsgWithContext{Msg: &tap.TapConnectReply{}, SeqNum: 3})
 
 	req := &tap.TapConnect{
 		TapName:      []byte("test-tap-name"),
@@ -497,7 +516,7 @@ func TestReceiveReplyAfterTimeoutMultiRequest(t *testing.T) {
 	ctx.ch.SetReplyTimeout(time.Millisecond * 100)
 
 	// first one request should work
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{}, false, 1)
+	ctx.mockVpp.MockReplyWithContext(mock.MsgWithContext{Msg: &vpe.ControlPingReply{}, SeqNum: 1})
 	err := ctx.ch.SendRequest(&vpe.ControlPing{}).ReceiveReply(&vpe.ControlPingReply{})
 	Expect(err).ShouldNot(HaveOccurred())
 
@@ -524,16 +543,22 @@ func TestReceiveReplyAfterTimeoutMultiRequest(t *testing.T) {
 	Expect(cnt).To(BeEquivalentTo(0))
 
 	// simulating late replies
+	msgs := []mock.MsgWithContext{}
 	for i := 1; i <= 3; i++ {
-		ctx.mockVpp.MockReplyWithSeqNum(&interfaces.SwInterfaceDetails{
-			SwIfIndex:     uint32(i),
-			InterfaceName: []byte("if-name-test"),
-		}, true, 2)
+		msgs = append(msgs, mock.MsgWithContext{
+			Msg: &interfaces.SwInterfaceDetails{
+				SwIfIndex:     uint32(i),
+				InterfaceName: []byte("if-name-test"),
+			},
+			Multipart: true,
+			SeqNum:    2,
+		})
 	}
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{}, true, 2)
+	msgs = append(msgs, mock.MsgWithContext{Msg: &vpe.ControlPingReply{}, Multipart: true, SeqNum: 2})
+	ctx.mockVpp.MockReplyWithContext(msgs...)
 
 	// normal reply for next request
-	ctx.mockVpp.MockReplyWithSeqNum(&tap.TapConnectReply{}, false, 3)
+	ctx.mockVpp.MockReplyWithContext(mock.MsgWithContext{Msg: &tap.TapConnectReply{}, SeqNum: 3})
 
 	req := &tap.TapConnect{
 		TapName:      []byte("test-tap-name"),
@@ -551,12 +576,12 @@ func TestInvalidMessageID(t *testing.T) {
 	defer ctx.teardownTest()
 
 	// first one request should work
-	ctx.mockVpp.MockReply(&vpe.ShowVersionReply{}, false)
+	ctx.mockVpp.MockReply(&vpe.ShowVersionReply{})
 	err := ctx.ch.SendRequest(&vpe.ShowVersion{}).ReceiveReply(&vpe.ShowVersionReply{})
 	Expect(err).ShouldNot(HaveOccurred())
 
 	// second should fail with error invalid message ID
-	ctx.mockVpp.MockReply(&vpe.ShowVersionReply{}, false)
+	ctx.mockVpp.MockReply(&vpe.ShowVersionReply{})
 	err = ctx.ch.SendRequest(&vpe.ControlPing{}).ReceiveReply(&vpe.ControlPingReply{})
 	Expect(err).Should(HaveOccurred())
 	Expect(err.Error()).To(ContainSubstring("invalid message ID"))
diff --git a/core/core_test.go b/core/core_test.go
index 981ff19..e4fbf63 100644
--- a/core/core_test.go
+++ b/core/core_test.go
@@ -62,7 +62,7 @@ func TestSimpleRequest(t *testing.T) {
 	ctx := setupTest(t, false)
 	defer ctx.teardownTest()
 
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: -5}, false)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: -5})
 
 	req := &vpe.ControlPing{}
 	reply := &vpe.ControlPingReply{}
@@ -85,10 +85,12 @@ func TestMultiRequest(t *testing.T) {
 	ctx := setupTest(t, false)
 	defer ctx.teardownTest()
 
+	msgs := []api.Message{}
 	for m := 0; m < 10; m++ {
-		ctx.mockVpp.MockReply(&interfaces.SwInterfaceDetails{}, true)
+		msgs = append(msgs, &interfaces.SwInterfaceDetails{})
 	}
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, true)
+	ctx.mockVpp.MockReply(msgs...)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 
 	// send multipart request
 	ctx.ch.ReqChan <- &api.VppRequest{Message: &interfaces.SwInterfaceDump{}, Multipart: true}
@@ -133,7 +135,7 @@ func TestNotifications(t *testing.T) {
 	ctx.mockVpp.MockReply(&interfaces.SwInterfaceSetFlags{
 		SwIfIndex:   3,
 		AdminUpDown: 1,
-	}, false)
+	})
 	ctx.mockVpp.SendMsg(0, []byte{0})
 
 	// receive the notification
@@ -204,7 +206,7 @@ func TestFullBuffer(t *testing.T) {
 
 	// send multiple requests, only one reply should be read
 	for i := 0; i < 20; i++ {
-		ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, false)
+		ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 		ctx.ch.ReqChan <- &api.VppRequest{Message: &vpe.ControlPing{}}
 	}
 
@@ -285,7 +287,7 @@ func TestSimpleRequestsWithSequenceNumbers(t *testing.T) {
 
 	var reqCtx []*api.RequestCtx
 	for i := 0; i < 10; i++ {
-		ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: int32(i)}, false)
+		ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: int32(i)})
 		req := &vpe.ControlPing{}
 		reqCtx = append(reqCtx, ctx.ch.SendRequest(req))
 	}
@@ -302,10 +304,12 @@ func TestMultiRequestsWithSequenceNumbers(t *testing.T) {
 	ctx := setupTest(t, false)
 	defer ctx.teardownTest()
 
+	msgs := []api.Message{}
 	for i := 0; i < 10; i++ {
-		ctx.mockVpp.MockReply(&interfaces.SwInterfaceDetails{SwIfIndex: uint32(i)}, true)
+		msgs = append(msgs, &interfaces.SwInterfaceDetails{SwIfIndex: uint32(i)})
 	}
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{}, true)
+	ctx.mockVpp.MockReply(msgs...)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{})
 
 	// send multipart request
 	reqCtx := ctx.ch.SendMultiRequest(&interfaces.SwInterfaceDump{})
@@ -336,7 +340,10 @@ func TestSimpleRequestWithTimeout(t *testing.T) {
 	defer ctx.teardownTest()
 
 	// reply for a previous timeouted requests to be ignored
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 1}, false,0)
+	ctx.mockVpp.MockReplyWithContext(mock.MsgWithContext{
+		Msg:    &vpe.ControlPingReply{Retval: 1},
+		SeqNum: 0,
+	})
 
 	// send reply later
 	req1 := &vpe.ControlPing{}
@@ -347,11 +354,19 @@ func TestSimpleRequestWithTimeout(t *testing.T) {
 	Expect(err).ToNot(BeNil())
 	Expect(err.Error()).To(HavePrefix("no reply received within the timeout period"))
 
-	// reply for the previous request
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 1}, false,1)
+	ctx.mockVpp.MockReplyWithContext(
+		// reply for the previous request
+		mock.MsgWithContext{
+			Msg:    &vpe.ControlPingReply{Retval: 1},
+			SeqNum: 1,
+		},
+		// reply for the next request
+		mock.MsgWithContext{
+			Msg:    &vpe.ControlPingReply{Retval: 2},
+			SeqNum: 2,
+		})
 
 	// next request
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: 2}, false)
 	req2 := &vpe.ControlPing{}
 	reqCtx2 := ctx.ch.SendRequest(req2)
 
@@ -375,7 +390,10 @@ func TestSimpleRequestsWithMissingReply(t *testing.T) {
 	reqCtx2 := ctx.ch.SendRequest(req2)
 
 	// third request with reply
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 3}, false, 3)
+	ctx.mockVpp.MockReplyWithContext(mock.MsgWithContext{
+		Msg:    &vpe.ControlPingReply{Retval: 3},
+		SeqNum: 3,
+	})
 	req3 := &vpe.ControlPing{}
 	reqCtx3 := ctx.ch.SendRequest(req3)
 
@@ -401,18 +419,42 @@ func TestMultiRequestsWithErrors(t *testing.T) {
 	ctx := setupTest(t, false)
 	defer ctx.teardownTest()
 
-	// reply for a previous timeouted requests to be ignored
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 1}, false,0xffff - 1)
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 1}, false,0xffff)
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 1}, false,0)
+	// replies for a previous timeouted requests to be ignored
+	msgs := []mock.MsgWithContext{}
+	msgs = append(msgs,
+		mock.MsgWithContext{
+			Msg:    &vpe.ControlPingReply{Retval: 1},
+			SeqNum: 0xffff - 1,
+		},
+		mock.MsgWithContext{
+			Msg:    &vpe.ControlPingReply{Retval: 1},
+			SeqNum: 0xffff,
+		},
+		mock.MsgWithContext{
+			Msg:    &vpe.ControlPingReply{Retval: 1},
+			SeqNum: 0,
+		})
 
 	for i := 0; i < 10; i++ {
-		ctx.mockVpp.MockReply(&interfaces.SwInterfaceDetails{SwIfIndex: uint32(i)}, true)
+		msgs = append(msgs,
+			mock.MsgWithContext{
+				Msg:       &interfaces.SwInterfaceDetails{SwIfIndex: uint32(i)},
+				SeqNum:    1,
+				Multipart: true,
+			})
 	}
 	// missing finalizing control ping
 
 	// reply for a next request
-	ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: 2}, false,2)
+	msgs = append(msgs,
+		mock.MsgWithContext{
+			Msg:       &vpe.ControlPingReply{Retval: 2},
+			SeqNum:    2,
+			Multipart: false,
+		})
+
+	// queue replies
+	ctx.mockVpp.MockReplyWithContext(msgs...)
 
 	// send multipart request
 	reqCtx := ctx.ch.SendMultiRequest(&interfaces.SwInterfaceDump{})
@@ -454,12 +496,12 @@ func TestRequestsOrdering(t *testing.T) {
 	// some replies will get thrown away
 
 	// first request
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: 1}, false)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: 1})
 	req1 := &vpe.ControlPing{}
 	reqCtx1 := ctx.ch.SendRequest(req1)
 
 	// second request
-	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: 2}, false)
+	ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: 2})
 	req2 := &vpe.ControlPing{}
 	reqCtx2 := ctx.ch.SendRequest(req2)
 
@@ -484,11 +526,9 @@ func TestCycleOverSetOfSequenceNumbers(t *testing.T) {
 	numIters := 0xffff + 100
 	reqCtx := make(map[int]*api.RequestCtx)
 
-	var seqNum uint16 = 0
-	for i := 0; i < numIters + 30 /* receiver is 30 reqs behind */; i++ {
-		seqNum++
+	for i := 0; i < numIters+30; /* receiver is 30 reqs behind */ i++ {
 		if i < numIters {
-			ctx.mockVpp.MockReplyWithSeqNum(&vpe.ControlPingReply{Retval: int32(i)}, false, seqNum)
+			ctx.mockVpp.MockReply(&vpe.ControlPingReply{Retval: int32(i)})
 			req := &vpe.ControlPing{}
 			reqCtx[i] = ctx.ch.SendRequest(req)
 		}
@@ -496,7 +536,7 @@ func TestCycleOverSetOfSequenceNumbers(t *testing.T) {
 			reply := &vpe.ControlPingReply{}
 			err := reqCtx[i-30].ReceiveReply(reply)
 			Expect(err).ShouldNot(HaveOccurred())
-			Expect(reply.Retval).To(BeEquivalentTo(i-30))
+			Expect(reply.Retval).To(BeEquivalentTo(i - 30))
 		}
 	}
-}
\ No newline at end of file
+}