move the version negotiation tests to a separate package

integrationtests/tools/qlog.go

@@ -0,0 +1,31 @@
+package tools
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"log"
+	"os"
+
+	"github.com/quic-go/quic-go/internal/utils"
+	"github.com/quic-go/quic-go/logging"
+	"github.com/quic-go/quic-go/qlog"
+)
+
+func NewQlogger(logger io.Writer) logging.Tracer {
+	return qlog.NewTracer(func(p logging.Perspective, connectionID []byte) io.WriteCloser {
+		role := "server"
+		if p == logging.PerspectiveClient {
+			role = "client"
+		}
+		filename := fmt.Sprintf("log_%x_%s.qlog", connectionID, role)
+		fmt.Fprintf(logger, "Creating %s.\n", filename)
+		f, err := os.Create(filename)
+		if err != nil {
+			log.Fatalf("failed to create qlog file: %s", err)
+			return nil
+		}
+		bw := bufio.NewWriter(f)
+		return utils.NewBufferedWriteCloser(bw, f)
+	})
+}