Calculate cart totals after running extensions

src/StoreApi/Routes/V1/AbstractCartRoute.php

@@ -78,7 +78,7 @@ public function __construct( SchemaController $schema_controller, AbstractSchema
 	 */
 	public function get_response( \WP_REST_Request $request ) {
 		$this->load_cart_session( $request );
-		$this->calculate_totals();
+		$this->cart_controller->calculate_totals();
 
 		if ( $this->requires_nonce( $request ) ) {
 			$nonce_check = $this->check_nonce( $request );
@@ -229,16 +229,6 @@ protected function cart_updated( \WP_REST_Request $request ) {
 		}
 	}
 
-	/**
-	 * Ensures the cart totals are calculated before an API response is generated.
-	 */
-	protected function calculate_totals() {
-		wc()->cart->get_cart();
-		wc()->cart->calculate_fees();
-		wc()->cart->calculate_shipping();
-		wc()->cart->calculate_totals();
-	}
-
 	/**
 	 * For non-GET endpoints, require and validate a nonce to prevent CSRF attacks.
 	 *

src/StoreApi/Routes/V1/CartUpdateCustomer.php

@@ -126,7 +126,7 @@ protected function get_route_post_response( \WP_REST_Request $request ) {
 
 		$customer->save();
 
-		$this->calculate_totals();
+		$this->cart_controller->calculate_totals();
 
 		return rest_ensure_response( $this->schema->get_item_response( $cart ) );
 	}

src/StoreApi/Schemas/V1/CartExtensionsSchema.php

@@ -69,12 +69,16 @@ public function get_item_response( $request = null ) {
 				400
 			);
 		}
+
+		$controller = new CartController();
+
 		if ( is_callable( $callback ) ) {
 			$callback( $request['data'] );
+			// We recalculate the cart if we had something to run.
+			$controller->calculate_totals();
 		}
 
-		$controller = new CartController();
-		$cart       = $controller->get_cart_instance();
+		$cart = $controller->get_cart_instance();
 
 		return rest_ensure_response( $this->cart_schema->get_item_response( $cart ) );
 	}

src/StoreApi/Utilities/CartController.php

@@ -32,6 +32,17 @@ public function load_cart() {
 		}
 	}
 
+	/**
+	 * Recalculates the cart totals.
+	 */
+	public function calculate_totals() {
+		$cart = $this->get_cart_instance();
+		$cart->get_cart();
+		$cart->calculate_fees();
+		$cart->calculate_shipping();
+		$cart->calculate_totals();
+	}
+
 	/**
 	 * Based on the core cart class but returns errors rather than rendering notices directly.
 	 *

tests/php/StoreApi/Routes/CartExtensions.php

@@ -6,16 +6,50 @@
 namespace Automattic\WooCommerce\Blocks\Tests\StoreApi\Routes;
 
 use Automattic\WooCommerce\Blocks\Tests\StoreApi\Routes\ControllerTestCase;
+use Automattic\WooCommerce\Blocks\Tests\Helpers\FixtureData;
 
 /**
  * Cart Controller Tests.
  */
 class CartExtensions extends ControllerTestCase {
 
+	/**
+	 * Setup test products data. Called before every test.
+	 */
+	public function setUp() {
+		parent::setUp();
+
+		$fixtures = new FixtureData();
+
+		$this->product = $fixtures->get_simple_product(
+			array(
+				'name'          => 'Test Product 1',
+				'regular_price' => 10,
+			)
+		);
+
+		wc_empty_cart();
+
+		wc()->cart->add_to_cart( $this->product->get_id(), 1 );
+
+		woocommerce_store_api_register_update_callback(
+			array(
+				'namespace' => 'valid-test-plugin',
+				'callback'  => function() {
+					add_action(
+						'woocommerce_cart_calculate_fees',
+						function() {
+							wc()->cart->add_fee( 'Surcharge', 10, true, 'standard' );
+						}
+					);
+				},
+			)
+		);
+	}
 	/**
 	 * Test getting cart with invalid namespace.
 	 */
-	public function test_post() {
+	public function test_invalid_namespace() {
 		$request = new \WP_REST_Request( 'POST', '/wc/store/v1/cart/extensions' );
 		$request->set_header( 'Nonce', wp_create_nonce( 'wc_store_api' ) );
 		$request->set_body_params(
@@ -28,4 +62,26 @@ public function test_post() {
 			400
 		);
 	}
+
+	/**
+	 * Test getting cart with invalid namespace.
+	 */
+	public function test_cart_being_updated() {
+		$request = new \WP_REST_Request( 'POST', '/wc/store/v1/cart/extensions' );
+		$request->set_header( 'Nonce', wp_create_nonce( 'wc_store_api' ) );
+		$request->set_body_params(
+			array(
+				'namespace' => 'valid-test-plugin',
+			)
+		);
+		$this->assertAPIResponse(
+			$request,
+			200,
+			array(
+				'totals' => array(
+					'total_fees' => '1000',
+				),
+			)
+		);
+	}
 }