add-custom-product-data-tab.php

/**
 * Add a custom product data tab.
 */

function wb_woo_new_product_tab( $tabs ) {

	// Adds the new tab.

	$tabs['test_tab'] = array(
		'title'    => __( 'New Product Tab', 'woocommerce' ),
		'priority' => 50,
		'callback' => 'wb_woo_new_product_tab_content',
	);

	return $tabs;

}
/**
 * Custom product data tab content.
 */
function wb_woo_new_product_tab_content() {

	// The new tab content.

	echo '<h2>New Product Tab</h2>';
	echo '<p>Here\'s your new product tab.</p>';

}
add_filter( 'woocommerce_product_tabs', 'wb_woo_new_product_tab' );