Build form properly for CRM_Financial_Form_PaymentEditTest::testSubmitOnCheckNumberChange

tests/phpunit/CRM/Financial/Form/PaymentEditTest.php

@@ -124,6 +124,7 @@ class CRM_Financial_Form_PaymentEditTest extends CiviUnitTestCase {
       'check_number' => $checkNumber1,
       'contribution_status_id' => CRM_Core_PseudoConstant::getKey('CRM_Contribute_BAO_Contribution', 'contribution_status_id', 'Completed'),
     ]);
+    $form->buildForm();
     $form->postProcess();
     $contribution = $this->callAPISuccessGetSingle('Contribution', ['contact_id' => $this->_individualID]);
     $payments = CRM_Contribute_BAO_Contribution::getPaymentInfo($contribution['id'], 'contribute', TRUE);