quic: add test helpers for acking packets

Add connTest methods to send the conn-under-test an ACK
for the latest packet it sent, or for all packets in the
number space it last sent in.

For golang/go#58547

Change-Id: Id35cad9bddf9dd32074dc121fd360a65b989fb4b
Reviewed-on: https://go-review.googlesource.com/c/net/+/522055
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

internal/quic/conn_id_test.go

@@ -264,7 +264,7 @@ func TestConnIDPeerRequestsRetirement(t *testing.T) {
 		packetType1RTT, debugFrameRetireConnectionID{
 			seq: 0,
 		})
-	if got, want := tc.sentFramePacket.dstConnID, testPeerConnID(1); !bytes.Equal(got, want) {
+	if got, want := tc.lastPacket.dstConnID, testPeerConnID(1); !bytes.Equal(got, want) {
 		t.Fatalf("used destination conn id {%x}, want {%x}", got, want)
 	}
 }
@@ -467,7 +467,7 @@ func TestConnIDUsePreferredAddressConnID(t *testing.T) {
 		packetType1RTT, debugFrameRetireConnectionID{
 			seq: 0,
 		})
-	if got, want := tc.sentFramePacket.dstConnID, cid; !bytes.Equal(got, want) {
+	if got, want := tc.lastPacket.dstConnID, cid; !bytes.Equal(got, want) {
 		t.Fatalf("used destination conn id {%x}, want {%x} from preferred address transport parameter", got, want)
 	}
 }

internal/quic/conn_loss_test.go

@@ -271,12 +271,7 @@ func TestLostStreamPartialLoss(t *testing.T) {
 				data: data[i : i+1],
 			})
 		if i%2 == 0 {
-			num := tc.sentFramePacket.num
-			tc.writeFrames(packetType1RTT, debugFrameAck{
-				ranges: []i64range[packetNumber]{
-					{num, num + 1},
-				},
-			})
+			tc.writeAckForLatest()
 		}
 	}
 	const pto = false

internal/quic/conn_test.go

@@ -137,10 +137,10 @@ type testConn struct {
 
 	// Datagrams, packets, and frames sent by the conn,
 	// but not yet processed by the test.
-	sentDatagrams   [][]byte
-	sentPackets     []*testPacket
-	sentFrames      []debugFrame
-	sentFramePacket *testPacket
+	sentDatagrams [][]byte
+	sentPackets   []*testPacket
+	sentFrames    []debugFrame
+	lastPacket    *testPacket
 
 	// Frame types to ignore in tests.
 	ignoreFrames map[byte]bool
@@ -388,6 +388,28 @@ func (tc *testConn) writeFrames(ptype packetType, frames ...debugFrame) {
 	tc.write(d)
 }
 
+// writeAckForAll sends the Conn a datagram containing an ack for all packets up to the
+// last one received.
+func (tc *testConn) writeAckForAll() {
+	if tc.lastPacket == nil {
+		return
+	}
+	tc.writeFrames(tc.lastPacket.ptype, debugFrameAck{
+		ranges: []i64range[packetNumber]{{0, tc.lastPacket.num + 1}},
+	})
+}
+
+// writeAckForLatest sends the Conn a datagram containing an ack for the
+// most recent packet received.
+func (tc *testConn) writeAckForLatest() {
+	if tc.lastPacket == nil {
+		return
+	}
+	tc.writeFrames(tc.lastPacket.ptype, debugFrameAck{
+		ranges: []i64range[packetNumber]{{tc.lastPacket.num, tc.lastPacket.num + 1}},
+	})
+}
+
 // ignoreFrame hides frames of the given type sent by the Conn.
 func (tc *testConn) ignoreFrame(frameType byte) {
 	tc.ignoreFrames[frameType] = true
@@ -423,6 +445,7 @@ func (tc *testConn) readPacket() *testPacket {
 	}
 	p := tc.sentPackets[0]
 	tc.sentPackets = tc.sentPackets[1:]
+	tc.lastPacket = p
 	return p
 }
 
@@ -435,12 +458,11 @@ func (tc *testConn) readFrame() (debugFrame, packetType) {
 		if p == nil {
 			return nil, packetTypeInvalid
 		}
-		tc.sentFramePacket = p
 		tc.sentFrames = p.frames
 	}
 	f := tc.sentFrames[0]
 	tc.sentFrames = tc.sentFrames[1:]
-	return f, tc.sentFramePacket.ptype
+	return f, tc.lastPacket.ptype
 }
 
 // wantDatagram indicates that we expect the Conn to send a datagram.

internal/quic/stream_test.go

@@ -193,9 +193,7 @@ func TestStreamWriteBlockedByWriteBufferLimit(t *testing.T) {
 		tc.wantIdle("no STREAM_DATA_BLOCKED, we're blocked locally not by flow control")
 
 		// ACK for previously-sent data allows making more progress.
-		tc.writeFrames(packetType1RTT, debugFrameAck{
-			ranges: []i64range[packetNumber]{{0, tc.sentFramePacket.num + 1}},
-		})
+		tc.writeAckForAll()
 		tc.wantFrame("ACK for previous data allows making progress",
 			packetType1RTT, debugFrameStream{
 				id:   s.id,
@@ -968,9 +966,7 @@ func TestStreamCloseWaitsForAcks(t *testing.T) {
 	if _, err := closing.result(); err != errNotDone {
 		t.Fatalf("s.CloseContext() = %v, want it to block waiting for acks", err)
 	}
-	tc.writeFrames(packetType1RTT, debugFrameAck{
-		ranges: []i64range[packetNumber]{{0, tc.sentFramePacket.num + 1}},
-	})
+	tc.writeAckForAll()
 	if _, err := closing.result(); err != nil {
 		t.Fatalf("s.CloseContext() = %v, want nil (all data acked)", err)
 	}
@@ -983,9 +979,7 @@ func TestStreamCloseUnblocked(t *testing.T) {
 	}{{
 		name: "data received",
 		unblock: func(tc *testConn, s *Stream) {
-			tc.writeFrames(packetType1RTT, debugFrameAck{
-				ranges: []i64range[packetNumber]{{0, tc.sentFramePacket.num + 1}},
-			})
+			tc.writeAckForAll()
 		},
 	}, {
 		name: "stop sending received",
@@ -1135,12 +1129,7 @@ func TestStreamPeerStopSendingForActiveStream(t *testing.T) {
 			t.Errorf("s.Write() after STOP_SENDING = %v, %v; want error", n, err)
 		}
 		// This ack will result in some of the previous frames being marked as lost.
-		tc.writeFrames(packetType1RTT, debugFrameAck{
-			ranges: []i64range[packetNumber]{{
-				tc.sentFramePacket.num,
-				tc.sentFramePacket.num + 1,
-			}},
-		})
+		tc.writeAckForLatest()
 		tc.wantIdle("lost STREAM frames for reset stream are not resent")
 	})
 }

internal/quic/tls_test.go

@@ -266,7 +266,7 @@ func (tc *testConn) uncheckedHandshake() {
 			debugFrameAck{
 				ackDelay: unscaledAckDelayFromDuration(
 					maxAckDelay, ackDelayExponent),
-				ranges: []i64range[packetNumber]{{0, tc.sentFramePacket.num + 1}},
+				ranges: []i64range[packetNumber]{{0, tc.lastPacket.num + 1}},
 			})
 	} else {
 		tc.wantIdle("initial frames are ignored")