refactor(netxlite): finish grouping tests (#488)

They are now more readable. I'll do another pass and start
separating integration testing from unit testing.

I think we need to have some always on integration testing
for netxlite that runs on macOS, linux, and windows.

See https://github.com/ooni/probe/issues/1591

internal/netxlite/integration_test.go

@@ -1,12 +1,15 @@
 package netxlite_test
 
 import (
+	"context"
 	"crypto/tls"
+	"net"
 	"net/http"
 	"testing"
 
 	"github.com/apex/log"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
+	utls "gitlab.com/yawning/utls.git"
 )
 
 func TestHTTPTransport(t *testing.T) {
@@ -49,3 +52,21 @@ func TestHTTP3Transport(t *testing.T) {
 		txp.CloseIdleConnections()
 	})
 }
+
+func TestUTLSHandshaker(t *testing.T) {
+	t.Run("with chrome fingerprint", func(t *testing.T) {
+		h := netxlite.NewTLSHandshakerUTLS(log.Log, &utls.HelloChrome_Auto)
+		cfg := &tls.Config{ServerName: "google.com"}
+		conn, err := net.Dial("tcp", "google.com:443")
+		if err != nil {
+			t.Fatal("unexpected error", err)
+		}
+		conn, _, err = h.Handshake(context.Background(), conn, cfg)
+		if err != nil {
+			t.Fatal("unexpected error", err)
+		}
+		if conn == nil {
+			t.Fatal("nil connection")
+		}
+	})
+}