feat: tlsmiddlebox experiment (#817)

See https://github.com/ooni/probe/issues/2124

internal/engine/experiment/tlsmiddlebox/dialer_test.go

@@ -0,0 +1,54 @@
+package tlsmiddlebox
+
+import (
+	"context"
+	"io"
+	"net"
+	"testing"
+
+	"github.com/ooni/probe-cli/v3/internal/model/mocks"
+	"github.com/ooni/probe-cli/v3/internal/netxlite"
+)
+
+func TestDialerWithTTL(t *testing.T) {
+	t.Run("DialContext on success", func(t *testing.T) {
+		t.Run("on success", func(t *testing.T) {
+			expectedConn := &mocks.Conn{}
+			d := &dialerTTLWrapper{
+				Dialer: &mocks.Dialer{
+					MockDialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
+						return expectedConn, nil
+					},
+				},
+			}
+			ctx := context.Background()
+			conn, err := d.DialContext(ctx, "", "")
+			if err != nil {
+				t.Fatal(err)
+			}
+			errWrapperConn := conn.(*dialerTTLWrapperConn)
+			if errWrapperConn.Conn != expectedConn {
+				t.Fatal("unexpected conn")
+			}
+		})
+
+		t.Run("on failure", func(t *testing.T) {
+			expectedErr := io.EOF
+			d := &dialerTTLWrapper{
+				Dialer: &mocks.Dialer{
+					MockDialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
+						return nil, expectedErr
+					},
+				},
+			}
+			ctx := context.Background()
+			conn, err := d.DialContext(ctx, "", "")
+			if err == nil || err.Error() != netxlite.FailureEOFError {
+				t.Fatal("unexpected err", err)
+			}
+			if conn != nil {
+				t.Fatal("expected nil conn")
+			}
+		})
+	})
+}