refactor(netxlite): improve tests for http and http3 (#487)

* refactor(netxlite): improve tests for http and http3

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

* Update internal/netxlite/http3.go

internal/netxlite/integration_test.go

@@ -0,0 +1,51 @@
+package netxlite_test
+
+import (
+	"crypto/tls"
+	"net/http"
+	"testing"
+
+	"github.com/apex/log"
+	"github.com/ooni/probe-cli/v3/internal/netxlite"
+)
+
+func TestHTTPTransport(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+
+	t.Run("works as intended", func(t *testing.T) {
+		d := netxlite.NewDialerWithResolver(log.Log, netxlite.NewResolverSystem(log.Log))
+		td := netxlite.NewTLSDialer(d, netxlite.NewTLSHandshakerStdlib(log.Log))
+		txp := netxlite.NewHTTPTransport(log.Log, d, td)
+		client := &http.Client{Transport: txp}
+		resp, err := client.Get("https://www.google.com/robots.txt")
+		if err != nil {
+			t.Fatal(err)
+		}
+		resp.Body.Close()
+		client.CloseIdleConnections()
+	})
+}
+
+func TestHTTP3Transport(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+
+	t.Run("works as intended", func(t *testing.T) {
+		d := netxlite.NewQUICDialerWithResolver(
+			netxlite.NewQUICListener(),
+			log.Log,
+			netxlite.NewResolverSystem(log.Log),
+		)
+		txp := netxlite.NewHTTP3Transport(d, &tls.Config{})
+		client := &http.Client{Transport: txp}
+		resp, err := client.Get("https://www.google.com/robots.txt")
+		if err != nil {
+			t.Fatal(err)
+		}
+		resp.Body.Close()
+		txp.CloseIdleConnections()
+	})
+}