WC_Tax::get_base_tax_rates PHP Method

    public static function get_base_tax_rates($tax_class = '')
    {
        return apply_filters('woocommerce_base_tax_rates', self::find_rates(array('country' => WC()->countries->get_base_country(), 'state' => WC()->countries->get_base_state(), 'postcode' => WC()->countries->get_base_postcode(), 'city' => WC()->countries->get_base_city(), 'tax_class' => $tax_class)), $tax_class);
    }

 /**
  * Get rates.
  */
 public function test_get_base_tax_rates()
 {
     global $wpdb;
     $wpdb->query("DELETE FROM {$wpdb->prefix}woocommerce_tax_rates");
     $wpdb->query("DELETE FROM {$wpdb->prefix}woocommerce_tax_rate_locations");
     $tax_rate = array('tax_rate_country' => 'GB', 'tax_rate_state' => '', 'tax_rate' => '20.0000', 'tax_rate_name' => 'VAT', 'tax_rate_priority' => '1', 'tax_rate_compound' => '0', 'tax_rate_shipping' => '1', 'tax_rate_order' => '1', 'tax_rate_class' => '');
     $tax_rate_id = WC_Tax::_insert_tax_rate($tax_rate);
     $tax_rates = WC_Tax::get_base_tax_rates();
     $this->assertEquals($tax_rates, array($tax_rate_id => array('rate' => '20.0000', 'label' => 'VAT', 'shipping' => 'yes', 'compound' => 'no')));
     WC_Tax::_delete_tax_rate($tax_rate_id);
 }