use synctest to make the send queue tests fully deterministic (#5302)

send_queue_test.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/quic-go/quic-go/internal/protocol"
+	"github.com/quic-go/quic-go/internal/synctest"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -20,6 +21,7 @@ func getPacketWithContents(b []byte) *packetBuffer {
 }
 
 func TestSendQueueSendOnePacket(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
 		mockCtrl := gomock.NewController(t)
 		c := NewMockSendConn(mockCtrl)
 		q := newSendQueue(c)
@@ -36,22 +38,27 @@ func TestSendQueueSendOnePacket(t *testing.T) {
 		}()
 
 		q.Send(getPacketWithContents([]byte("foobar")), 10, protocol.ECT1)
+		synctest.Wait()
 
 		select {
 		case <-written:
-	case <-time.After(time.Second):
-		t.Fatal("timeout")
+		default:
+			t.Fatal("write should have returned")
 		}
 
 		q.Close()
+		synctest.Wait()
+
 		select {
 		case <-done:
-	case <-time.After(time.Second):
-		t.Fatal("timeout")
+		default:
+			t.Fatal("Run should have returned")
 		}
+	})
 }
 
 func TestSendQueueBlocking(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
 		mockCtrl := gomock.NewController(t)
 		c := NewMockSendConn(mockCtrl)
 		q := newSendQueue(c)
@@ -76,7 +83,7 @@ func TestSendQueueBlocking(t *testing.T) {
 		}()
 
 		// +1, since one packet will be queued in the Write call
-	for i := 0; i < sendQueueCapacity+1; i++ {
+		for i := range sendQueueCapacity + 1 {
 			require.False(t, q.WouldBlock())
 			q.Send(getPacketWithContents([]byte("foobar")), 10, protocol.ECT1)
 			// make sure that the first packet is actually enqueued in the Write call
@@ -117,28 +124,34 @@ func TestSendQueueBlocking(t *testing.T) {
 			close(closed)
 		}()
 
+		synctest.Wait()
+
 		select {
 		case <-closed:
 			t.Fatal("Close should have blocked")
-	case <-time.After(scaleDuration(10 * time.Millisecond)):
+		default:
 		}
 
-	for i := 0; i < sendQueueCapacity; i++ {
+		for range sendQueueCapacity {
 			blockWrite <- struct{}{}
 		}
+		synctest.Wait()
+
 		select {
 		case <-closed:
-	case <-time.After(time.Second):
-		t.Fatal("timeout")
+		default:
+			t.Fatal("Close should have returned")
 		}
 		select {
 		case <-done:
-	case <-time.After(time.Second):
-		t.Fatal("timeout")
+		default:
+			t.Fatal("Run should have returned")
 		}
+	})
 }
 
 func TestSendQueueWriteError(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
 		mockCtrl := gomock.NewController(t)
 		c := NewMockSendConn(mockCtrl)
 		q := newSendQueue(c)
@@ -149,27 +162,32 @@ func TestSendQueueWriteError(t *testing.T) {
 		errChan := make(chan error, 1)
 		go func() { errChan <- q.Run() }()
 
+		synctest.Wait()
+
 		select {
 		case err := <-errChan:
 			require.ErrorIs(t, err, assert.AnError)
-	case <-time.After(time.Second):
-		t.Fatal("timeout")
+		default:
+			t.Fatal("Run should have returned")
 		}
 
 		// further calls to Send should not block
 		sent := make(chan struct{})
 		go func() {
 			defer close(sent)
-		for i := 0; i < 2*sendQueueCapacity; i++ {
+			for range 2 * sendQueueCapacity {
 				q.Send(getPacketWithContents([]byte("raboof")), 6, protocol.ECNNon)
 			}
 		}()
 
+		synctest.Wait()
+
 		select {
 		case <-sent:
-	case <-time.After(time.Second):
-		t.Fatal("timeout")
+		default:
+			t.Fatal("Send should have returned")
 		}
+	})
 }
 
 func TestSendQueueSendProbe(t *testing.T) {