WooCommerce Class dosen’t exist

For official release installed or not,

/**
 * Check if WooCommerce is active
 **/
$plugin_path = trailingslashit( WP_PLUGIN_DIR ) . 'woocommerce/woocommerce.php';

if (
    in_array( $plugin_path, wp_get_active_and_valid_plugins() )
    || in_array( $plugin_path, wp_get_active_network_plugins() )
) {
    // Custom code here. WooCommerce is active, however it has not 
    // necessarily initialized (when that is important, consider
    // using the `woocommerce_init` action).
}

You could check the article from the woocommerce that it could be more compatiable.