fix: tokenized ECE do not show button when missing billing email

changelog/fix-tokenized-ece-pay-for-order-without-billing-email

@@ -0,0 +1,5 @@
+Significance: patch
+Type: fix
+Comment: fix: tokenized ECE do not show button when missing billing email
+
+

includes/express-checkout/class-wc-payments-express-checkout-button-helper.php

@@ -412,7 +412,7 @@ public function should_show_express_checkout_button() {
 
 		// Order total doesn't matter for Pay for Order page. Thus, this page should always display payment buttons.
 		if ( $this->is_pay_for_order_page() ) {
-			return true;
+			return $this->is_pay_for_order_supported();
 		}
 
 		// Non-shipping product and tax is calculated based on shopper billing address. Excludes Pay for Order page.
@@ -749,6 +749,38 @@ public function get_product_data() {
 		return apply_filters( 'wcpay_payment_request_product_data', $data, $product );
 	}
 
+	/**
+	 * The Store API doesn't allow checkout without the billing email address present on the order data.
+	 * https://github.com/woocommerce/woocommerce/issues/48540
+	 *
+	 * @return bool
+	 */
+	private function is_pay_for_order_supported() {
+		if ( ! WC_Payments_Features::is_tokenized_cart_ece_enabled() ) {
+			return true;
+		}
+
+		$order_id = absint( get_query_var( 'order-pay' ) );
+		if ( 0 === $order_id ) {
+			return false;
+		}
+
+		$order = wc_get_order( $order_id );
+		if ( ! is_a( $order, 'WC_Order' ) ) {
+			return false;
+		}
+
+		// we don't need to check its validity or value, we just need to ensure a billing email is present.
+		$billing_email = $order->get_billing_email();
+		if ( ! empty( $billing_email ) ) {
+			return true;
+		}
+
+		Logger::log( 'Billing email not present ( Express Checkout Element button disabled )' );
+
+		return false;
+	}
+
 	/**
 	 * Whether product page has a supported product.
 	 *

tests/unit/express-checkout/test-class-wc-payments-express-checkout-button-helper.php

@@ -104,6 +104,7 @@ public function tear_down() {
 		remove_filter( 'wc_tax_enabled', '__return_false' );
 		remove_filter( 'pre_option_woocommerce_tax_display_cart', [ $this, '__return_excl' ] );
 		remove_filter( 'pre_option_woocommerce_tax_display_cart', [ $this, '__return_incl' ] );
+		delete_option( '_wcpay_feature_tokenized_cart_ece' );
 
 		parent::tear_down();
 	}
@@ -208,6 +209,30 @@ function () {
 		remove_all_filters( 'wcpay_payment_request_total_label_suffix' );
 	}
 
+	public function test_should_show_express_checkout_button_for_tokenized_ece_with_billing_email() {
+		global $wp;
+		global $wp_query;
+
+		$this->mock_wcpay_account
+			->method( 'is_stripe_connected' )
+			->willReturn( true );
+		WC_Payments::mode()->dev();
+		$_GET['pay_for_order'] = true;
+
+		// Total is 100 USD, which is above both payment methods (Affirm and AfterPay) minimums.
+		$order                = WC_Helper_Order::create_order( 1, 100 );
+		$order_id             = $order->get_id();
+		$wp->query_vars       = [ 'order-pay' => strval( $order_id ) ];
+		$wp_query->query_vars = [ 'order-pay' => strval( $order_id ) ];
+
+		update_option( '_wcpay_feature_tokenized_cart_ece', '1' );
+		add_filter( 'woocommerce_is_checkout', '__return_true' );
+
+		$this->assertTrue( $this->system_under_test->should_show_express_checkout_button() );
+
+		remove_filter( 'woocommerce_is_checkout', '__return_true' );
+	}
+
 	public function test_should_show_express_checkout_button_for_non_shipping_but_price_includes_tax() {
 		$this->mock_wcpay_account
 			->method( 'is_stripe_connected' )
@@ -229,7 +254,6 @@ public function test_should_show_express_checkout_button_for_non_shipping_but_pr
 		remove_filter( 'pre_option_woocommerce_tax_display_cart', [ $this, '__return_incl' ] );
 	}
 
-
 	public function test_should_not_show_express_checkout_button_for_non_shipping_but_price_does_not_include_tax() {
 		$this->mock_wcpay_account
 			->method( 'is_stripe_connected' )