Add API for retrieving paypal order

api/order-functions.php

@@ -15,10 +15,36 @@ use Exception;
 use InvalidArgumentException;
 use RuntimeException;
 use WC_Order;
+use WooCommerce\PayPalCommerce\ApiClient\Endpoint\OrderEndpoint;
+use WooCommerce\PayPalCommerce\ApiClient\Entity\Order;
 use WooCommerce\PayPalCommerce\PPCP;
 use WooCommerce\PayPalCommerce\WcGateway\Gateway\PayPalGateway;
 use WooCommerce\PayPalCommerce\WcGateway\Processor\AuthorizedPaymentsProcessor;
 
+/**
+ * Returns the PayPal order.
+ *
+ * @param string|WC_Order $paypal_id_or_wc_order The ID of PayPal order or a WC order (with the ID in meta).
+ * @throws InvalidArgumentException When the argument cannot be used for retrieving the order.
+ * @throws Exception When the operation fails.
+ */
+function ppcp_get_paypal_order( $paypal_id_or_wc_order ): Order {
+	if ( $paypal_id_or_wc_order instanceof WC_Order ) {
+		$paypal_id_or_wc_order = $paypal_id_or_wc_order->get_meta( PayPalGateway::ORDER_ID_META_KEY );
+		if ( ! $paypal_id_or_wc_order ) {
+			throw new InvalidArgumentException( 'PayPal order ID not found in meta.' );
+		}
+	}
+	if ( ! is_string( $paypal_id_or_wc_order ) ) {
+		throw new InvalidArgumentException( 'Invalid PayPal order ID, string expected.' );
+	}
+
+	$order_endpoint = PPCP::container()->get( 'api.endpoint.order' );
+	assert( $order_endpoint instanceof OrderEndpoint );
+
+	return $order_endpoint->order( $paypal_id_or_wc_order );
+}
+
 /**
  * Captures the PayPal order.
  *

tests/PHPUnit/Api/GetOrderTest.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace WooCommerce\PayPalCommerce\Api;
+
+use InvalidArgumentException;
+use Mockery;
+use RuntimeException;
+use WC_Order;
+use WooCommerce\PayPalCommerce\ApiClient\Endpoint\OrderEndpoint;
+use WooCommerce\PayPalCommerce\ApiClient\Entity\Order;
+use WooCommerce\PayPalCommerce\ModularTestCase;
+use WooCommerce\PayPalCommerce\WcGateway\Gateway\PayPalGateway;
+
+class GetOrderTest extends ModularTestCase
+{
+	private $orderEndpoint;
+
+	public function setUp(): void {
+		parent::setUp();
+
+		$this->orderEndpoint = Mockery::mock(OrderEndpoint::class);
+
+		$this->bootstrapModule([
+			'api.endpoint.order' => function () {
+				return $this->orderEndpoint;
+			},
+		]);
+	}
+
+	public function testSuccess(): void {
+		$this->orderEndpoint
+			->expects('order')
+			->with('123abc')
+			->andReturn(Mockery::mock(Order::class))
+			->once();
+
+		ppcp_get_paypal_order('123abc');
+	}
+
+	public function testSuccessWithOrder(): void {
+		$wcOrder = Mockery::mock(WC_Order::class);
+		$wcOrder->expects('get_meta')
+			->with(PayPalGateway::ORDER_ID_META_KEY)
+			->andReturn('123abc');
+
+		$this->orderEndpoint
+			->expects('order')
+			->with('123abc')
+			->andReturn(Mockery::mock(Order::class))
+			->once();
+
+		ppcp_get_paypal_order($wcOrder);
+	}
+
+	public function testOrderWithoutId(): void {
+		$wcOrder = Mockery::mock(WC_Order::class);
+		$wcOrder->expects('get_meta')
+			->with(PayPalGateway::ORDER_ID_META_KEY)
+			->andReturn(false);
+
+		$this->expectException(InvalidArgumentException::class);
+
+		ppcp_get_paypal_order($wcOrder);
+	}
+
+	public function testFailure(): void {
+		$this->orderEndpoint
+			->expects('order')
+			->with('123abc')
+			->andThrow(new RuntimeException())
+			->once();
+
+		$this->expectException(RuntimeException::class);
+
+		ppcp_get_paypal_order('123abc');
+	}
+
+	public function testInvalidId(): void {
+		$this->expectException(InvalidArgumentException::class);
+
+		ppcp_get_paypal_order(123);
+	}
+}