I am programming a payment plugin for woocommerce, for the purposes of testing it I need to print the values of $response, I have treated withecho, print_r andvar_dump, but when I make the purchase process it does not print in any side.

How can I do to visualize its content when buying a product.
(After entering the card details and making the purchase process I need to see those values)

Part of the plugin code:

    $payload = array(
      "key_id"  => $key_id,
      "hash" => $hash,
      "time" => $time,
      "amount" => $customer_order->order_total,
      "ccnumber" => str_replace( array(' ', '-' ), '', $_POST['bac_payment-card-number'] ),
      "ccexp" => str_replace( array( '/', ' '), '', $_POST['bac_payment-card-expiry'] ),
      "orderid" => $orderid,
      "cvv" => ( isset( $_POST['bac_payment-card-cvc'] ) ) ? $_POST['bac_payment-card-cvc'] : '',
      "type" => "auth",);
    // Send this payload to Authorize.net for processing
    $response = wp_remote_post( $environment_url, array(
      'method'    => 'POST',
      'body'      => http_build_query( $payload ),
      'timeout'   => 90,
      'sslverify' => false,
    ) );

//***********
//when I make a purchase I need to see these values
//************
var_dump($response);
var_dump($response_body);

die()