Do not attempt to cache orders during order creation (#37569)

plugins/woocommerce/changelog/fix-order-cache-order-type

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fix
+
+Do not attempt to cache order during order creation (HPOS).

plugins/woocommerce/includes/abstracts/abstract-wc-order.php

@@ -218,7 +218,7 @@ abstract class WC_Abstract_Order extends WC_Abstract_Legacy_Order {
 
 			if ( OrderUtil::orders_cache_usage_is_enabled() ) {
 				$order_cache = wc_get_container()->get( OrderCache::class );
-				$order_cache->update_if_cached( $this );
+				$order_cache->remove( $this->get_id() );
 			}
 
 			/**

plugins/woocommerce/tests/php/includes/abstracts/class-wc-abstract-order-test.php

@@ -269,4 +269,23 @@ class WC_Abstract_Order_Test extends WC_Unit_Test_Case {
 		$this->assertEquals( $coupon->get_id(), $coupon_data['id'] );
 		$this->assertEquals( $coupon_code, $coupon_data['code'] );
 	}
+
+	/**
+	 * @testDox Cache does not interfere if wc_get_order returns a different class than WC_Order.
+	 */
+	public function test_cache_does_not_interferes_with_order_object() {
+		add_action(
+			'woocommerce_new_order',
+			function( $order_id ) {
+				// this makes the cache store a specific order class instance, but it's quickly replaced by a generic one
+				// as we're in the middle of a save and this gets executed before the logic in WC_Abstract_Order.
+				$order = wc_get_order( $order_id );
+			}
+		);
+		$order = new WC_Order();
+		$order->save();
+
+		$order = wc_get_order( $order->get_id() );
+		$this->assertInstanceOf( Automattic\WooCommerce\Admin\Overrides\Order::class, $order );
+	}
 }