Avoid a possible error when linking accounts due to the delay between Google APIs

src/API/Google/Ads.php

@@ -129,7 +129,7 @@ public function get_billing_status(): string {
 	 * @throws Exception When a link is unavailable.
 	 */
 	public function accept_merchant_link( int $merchant_id ) {
-		$link        = $this->get_merchant_link( $merchant_id );
+		$link        = $this->get_merchant_link( $merchant_id, 3 );
 		$link_status = $link->getStatus();
 		if ( $link_status === ProductLinkInvitationStatus::ACCEPTED ) {
 			return;
@@ -325,12 +325,17 @@ private function get_account_details( string $account ): ?array {
 	/**
 	 * Get the link from a merchant account.
 	 *
+	 * The invitation link may not be available in Google Ads immediately after
+	 * the invitation is sent from Google Merchant Center, so this method offers
+	 * a parameter to specify the number of retries.
+	 *
 	 * @param int $merchant_id Merchant Center account id.
+	 * @param int $attempts_left The number of attempts left to get the link.
 	 *
 	 * @return ProductLinkInvitation
 	 * @throws Exception When the merchant link hasn't been created.
 	 */
-	private function get_merchant_link( int $merchant_id ): ProductLinkInvitation {
+	private function get_merchant_link( int $merchant_id, int $attempts_left = 0 ): ProductLinkInvitation {
 		$res = ( new AdsProductLinkInvitationQuery() )
 			->set_client( $this->client, $this->options->get_ads_id() )
 			->where( 'product_link_invitation.status', [ ProductLinkInvitationStatus::name( ProductLinkInvitationStatus::ACCEPTED ), ProductLinkInvitationStatus::name( ProductLinkInvitationStatus::PENDING_APPROVAL ) ], 'IN' )
@@ -345,6 +350,10 @@ private function get_merchant_link( int $merchant_id ): ProductLinkInvitation {
 			}
 		}
 
+		if ( $attempts_left > 0 ) {
+			return $this->get_merchant_link( $merchant_id, $attempts_left - 1 );
+		}
+
 		throw new Exception( __( 'Merchant link is not available to accept', 'google-listings-and-ads' ) );
 	}
 }

tests/Unit/API/Google/AdsTest.php

@@ -179,6 +179,30 @@ public function test_accept_merchant_link_already_accepted() {
 		$this->ads->accept_merchant_link( self::TEST_MERCHANT_ID );
 	}
 
+	public function test_accept_merchant_link_with_retry_get_merchant_link() {
+		$this->options->method( 'get_ads_id' )->willReturn( self::TEST_ADS_ID );
+		$link = new ProductLinkInvitation();
+		$mc   = $this->createMock( MerchantCenterLinkInvitationIdentifier::class );
+
+		$mc
+			->expects( $this->exactly( 4 ) )
+			->method( 'getMerchantCenterId' )
+			->willReturnOnConsecutiveCalls(
+				self::TEST_MERCHANT_ID + 3,
+				self::TEST_MERCHANT_ID + 2,
+				self::TEST_MERCHANT_ID + 1,
+				self::TEST_MERCHANT_ID
+			);
+
+		$link->setStatus( ProductLinkInvitationStatus::PENDING_APPROVAL );
+		$link->setMerchantCenter( $mc );
+
+		$service = $this->generate_mc_link_mock( [ $link ] );
+		$service->expects( $this->once() )->method( 'updateProductLinkInvitation' );
+
+		$this->ads->accept_merchant_link( self::TEST_MERCHANT_ID );
+	}
+
 	public function test_accept_merchant_link() {
 		$this->options->method( 'get_ads_id' )->willReturn( self::TEST_ADS_ID );
 		$link = new ProductLinkInvitation();