Fix: Unable to process payment for $0 subscription with recurring coupon (#4429)

* update logic for calculating the `amount` for mandate option
- use subtotal if total is 0 due to free trial or coupon
- use subtotal only during a setup intent creation

* use the mandate logic from subscription trait

* update test

* add changelog

* mock the filter

---------

Co-authored-by: Wesley Rosa <[email protected]>

Author: Mayisha

changelog.txt

@@ -42,6 +42,7 @@
 * Tweak - Remove Payment Method Configurations fallback cache
 * Tweak - Update deprecation notice message to specify that legacy checkout experience has been deprecated since version 9.6.0
 * Update - Remove legacy checkout checkbox from settings
+* Fix - Fix payment processing for $0 subscription with recurring coupon
 * Dev - Add e2e tests to cover Affirm purchase flow
 
 = 9.5.3 - 2025-06-23 =

includes/class-wc-stripe-intent-controller.php

@@ -848,30 +848,13 @@ private function maybe_add_mandate_options( $request, $payment_method_type, $is_
 		}
 
 		if ( WC_Stripe_Payment_Methods::CARD === $payment_method_type && $order && $is_setup_intent ) {
-			$currency = $order->get_currency();
-			// We don't need to add mandate options if the currency is not supported for Indian recurring payment mandates.
-			if ( ! WC_Stripe_Helper::is_currency_supported_for_indian_recurring_payment_mandate( $currency ) ) {
-				return $request;
-			}
-
-			$mandate_options = [
-				'currency'        => strtolower( $currency ), // Currency is required for mandate options when creating a setup intent for card payment methods.
-				'reference'       => $order->get_id(),
-				'amount_type'     => 'fixed',
-				'amount'          => WC_Stripe_Helper::get_stripe_amount( $order->get_total(), $currency ),
-				'start_date'      => time(),
-				'interval'        => 'sporadic',
-				'supported_types' => [ 'india' ],
-			];
-
-			$request['payment_method_options'][ WC_Stripe_Payment_Methods::CARD ]['mandate_options'] = $mandate_options;
-
 			// Run the necessary filter to make sure correct mandate information is added for recurring card payments for subscriptions.
 			$request = apply_filters(
 				'wc_stripe_generate_create_intent_request',
 				$request,
 				$order,
-				null // $prepared_source parameter is not necessary for adding mandate information.
+				null, // $prepared_source parameter is not necessary for adding mandate information.
+				true // $is_setup_intent parameter is true for setup intents.
 			);
 		}
 

includes/compat/trait-wc-stripe-subscriptions.php

@@ -89,7 +89,7 @@ public function maybe_init_subscriptions() {
 		add_filter( 'wc_stripe_display_save_payment_method_checkbox', [ $this, 'display_save_payment_method_checkbox' ] );
 
 		// Add the necessary information to create a mandate to the payment intent.
-		add_filter( 'wc_stripe_generate_create_intent_request', [ $this, 'add_subscription_information_to_intent' ], 10, 3 );
+		add_filter( 'wc_stripe_generate_create_intent_request', [ $this, 'add_subscription_information_to_intent' ], 10, 4 );
 
 		/*
 		* WC subscriptions hooks into the "template_redirect" hook with priority 100.
@@ -758,7 +758,7 @@ public function validate_subscription_payment_meta( $payment_method_id, $payment
 	 * @param WC_Order $order            The renewal order.
 	 * @param object   $prepared_source  The source object.
 	 */
-	public function add_subscription_information_to_intent( $request, $order, $prepared_source ) {
+	public function add_subscription_information_to_intent( $request, $order, $prepared_source, $is_setup_intent = false ) {
 		// Just in case the order doesn't contain a subscription we return the base request.
 		if ( ! $this->has_subscription( $order->get_id() ) ) {
 			return $request;
@@ -797,7 +797,7 @@ public function add_subscription_information_to_intent( $request, $order, $prepa
 
 		// Add mandate options to request to create new mandate if mandate id does not already exist in a previous renewal or parent order.
 		// Note: This is for backwards compatibility if `_stripe_mandate_id` is not set.
-		$mandate_options = $this->create_mandate_options_for_order( $order, $subscriptions_for_renewal_order );
+		$mandate_options = $this->create_mandate_options_for_order( $order, $subscriptions_for_renewal_order, $is_setup_intent );
 		if ( ! empty( $mandate_options ) ) {
 			if ( ! isset( $request['payment_method_options']['card']['mandate_options'] ) ) {
 				$request['payment_method_options']['card']['mandate_options'] = [];
@@ -845,9 +845,10 @@ private function get_mandate_for_subscription( $order, $payment_method ) {
 	 *
 	 * @param WC_Order $order The renewal order.
 	 * @param WC_Subscription[] $subscriptions Subscriptions for the renewal order.
+	 * @param bool $is_setup_intent Whether the intent is a setup intent.
 	 * @return array the mandate_options for the subscription order.
 	 */
-	private function create_mandate_options_for_order( $order, $subscriptions ) {
+	private function create_mandate_options_for_order( $order, $subscriptions, $is_setup_intent = false ) {
 		$mandate_options = [];
 		$currency        = strtolower( $order->get_currency() );
 
@@ -895,6 +896,14 @@ private function create_mandate_options_for_order( $order, $subscriptions ) {
 				$sub_amount += WC_Stripe_Helper::get_stripe_amount( $sub->get_total(), $currency );
 			}
 
+			// If the total amount is 0 and it's a setup intent, then calculate the amount from the subscription subtotal.
+			// The total could be 0 if the subscription has a free trial or a coupon is used.
+			if ( 0 === $sub_amount && $is_setup_intent ) {
+				foreach ( $subscriptions as $sub ) {
+					$sub_amount += WC_Stripe_Helper::get_stripe_amount( $sub->get_subtotal(), $currency );
+				}
+			}
+
 			// Get the first subscription associated with this order.
 			$sub = reset( $subscriptions );
 
@@ -920,6 +929,11 @@ private function create_mandate_options_for_order( $order, $subscriptions ) {
 			$mandate_options['interval']    = 'sporadic';
 		}
 
+		// Currency is required for mandate options when creating a setup intent for card payment methods.
+		if ( $is_setup_intent ) {
+			$mandate_options['currency'] = $currency;
+		}
+
 		$mandate_options['amount']          = $sub_amount;
 		$mandate_options['reference']       = $order->get_id();
 		$mandate_options['start_date']      = time();

readme.txt

@@ -154,6 +154,7 @@ If you get stuck, you can ask for help in the [Plugin Forum](https://wordpress.o
 * Dev - Add Klarna e2e tests
 * Tweak - Update deprecation notice message to specify that legacy checkout experience has been deprecated since version 9.6.0
 * Update - Remove legacy checkout checkbox from settings
+* Fix - Fix payment processing for $0 subscription with recurring coupon
 * Dev - Add e2e tests to cover Affirm purchase flow
 
 [See changelog for full details across versions](https://raw.githubusercontent.com/woocommerce/woocommerce-gateway-stripe/trunk/changelog.txt).

tests/phpunit/Helpers/WC_Subscription.php

@@ -49,6 +49,24 @@ public function get_type() {
 		return $this->order_type;
 	}
 
+	/**
+	 * Get billing period.
+	 *
+	 * @return string
+	 */
+	public function get_billing_period() {
+		return 'month';
+	}
+
+	/**
+	 * Get billing interval.
+	 *
+	 * @return int
+	 */
+	public function get_billing_interval() {
+		return 1;
+	}
+
 	/**
 	 * Generates a URL to add or change the subscription's payment method from the my account page.
 	 *

tests/phpunit/Helpers/WC_Subscriptions_Switcher.php

@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * A helper class for setting up mocks for WC_Subscriptions_Switcher functions.
+ */
+class WC_Subscriptions_Switcher {
+
+	/**
+	 * Mock value for cart_contains_switches.
+	 *
+	 * @var array
+	 */
+	public static $cart_contains_switches = false;
+
+	public static function cart_contains_switches() {
+		return self::$cart_contains_switches;
+	}
+}

tests/phpunit/WC_Stripe_Intent_Controller_Test.php

@@ -8,6 +8,9 @@
 use WC_Stripe_Intent_Controller;
 use WC_Stripe_Payment_Methods;
 use WC_Stripe_UPE_Payment_Gateway;
+use WC_Subscription;
+use WC_Subscriptions_Switcher;
+use WC_Subscriptions_Helpers;
 use WooCommerce\Stripe\Tests\Helpers\WC_Helper_Order;
 use WP_UnitTestCase;
 
@@ -49,7 +52,7 @@ public function set_up() {
 		$this->order           = WC_Helper_Order::create_order();
 		$this->gateway         = $this->getMockBuilder( 'WC_Stripe_UPE_Payment_Gateway' )
 			->setConstructorArgs( [ $mock_account ] )
-			->setMethods( [ 'maybe_process_upe_redirect' ] )
+			->setMethods( [ 'maybe_process_upe_redirect', 'has_subscription' ] )
 			->getMock();
 		$this->mock_controller = $this->getMockBuilder( 'WC_Stripe_Intent_Controller' )
 			->disableOriginalConstructor()
@@ -58,6 +61,9 @@ public function set_up() {
 		$this->mock_controller->expects( $this->any() )
 			->method( 'get_gateway' )
 			->willReturn( $this->gateway );
+		$this->gateway->expects( $this->any() )
+			->method( 'has_subscription' )
+			->willReturn( true );
 	}
 
 	public function test_wether_default_capture_method_is_set_in_the_intent() {
@@ -479,17 +485,32 @@ public function test_create_and_confirm_setup_intent_error() {
 	}
 
 	/**
-	 * Test mandate options for card payment method in setup intent.
+	 * Test mandate options for card payment method in setup intent for subscription.
 	 */
-	public function test_mandate_options_for_card_setup_intent() {
+	public function test_mandate_options_for_card_setup_intent_for_subscription() {
+		// create a subscription
+		$subscription = new WC_Subscription();
+		$subscription->set_status( 'active' );
+		$subscription->set_total( 100 );
+		$subscription->set_currency( 'USD' );
+		$subscription->set_customer_id( 'cus_mock' );
+		$subscription->set_payment_method( 'pm_mock' );
+		$subscription->save();
+
+		WC_Subscriptions_Switcher::$cart_contains_switches         = false;
+		WC_Subscriptions_Helpers::$wcs_get_subscriptions_for_order = [ $subscription ];
+
+		// Manually add the subscription filter that would normally be added by maybe_init_subscriptions()
+		add_filter( 'wc_stripe_generate_create_intent_request', [ $this->gateway, 'add_subscription_information_to_intent' ], 10, 4 );
+
 		$payment_information = [
 			'payment_method'        => 'pm_mock',
-			'customer'             => 'cus_mock',
+			'customer'              => 'cus_mock',
 			'selected_payment_type' => WC_Stripe_Payment_Methods::CARD,
-			'payment_method_types' => [ WC_Stripe_Payment_Methods::CARD ],
-			'return_url'           => 'https://example.com/return',
-			'order'               => $this->order,
-			'use_stripe_sdk'      => 'true',
+			'payment_method_types'  => [ WC_Stripe_Payment_Methods::CARD ],
+			'return_url'            => 'https://example.com/return',
+			'order'                 => $subscription,
+			'use_stripe_sdk'        => 'true',
 		];
 
 		$test_request = function ( $preempt, $parsed_args, $url ) {

tests/phpunit/bootstrap.php

@@ -58,3 +58,4 @@ function _manually_load_plugin() {
 require_once __DIR__ . '/Helpers/WC_Subscriptions.php';
 require_once __DIR__ . '/Helpers/WC_Subscriptions_Cart.php';
 require_once __DIR__ . '/Helpers/WC_Subscriptions_Helpers.php';
+require_once __DIR__ . '/Helpers/WC_Subscriptions_Switcher.php';