email is not enough, we now need contact id to find the customer.

CRM/Stripe/Customer.php

@@ -17,8 +17,8 @@ class CRM_Stripe_Customer {
         throw new CRM_Core_Exception('Stripe Customer (find): Missing required parameter: ' . $required);
       }
     }
-    if (empty($params['email']) && empty($params['contact_id'])) {
-      throw new CRM_Core_Exception('Stripe Customer (find): One of email or contact_id is required');
+    if (empty($params['contact_id'])) {
+      throw new CRM_Core_Exception('Stripe Customer (find): contact_id is required');
     }
     $queryParams = [
       1 => [$params['contact_id'], 'String'],

tests/phpunit/CRM/Stripe/BaseTest.php

@@ -157,6 +157,7 @@ class CRM_Stripe_BaseTest extends \PHPUnit_Framework_TestCase implements Headles
         'address_zip' => '12345',
       ),
       'email' => $this->contact->email,
+      'contactID' => $this->contact->id,
       'description' => 'Test from Stripe Test Code',
       'currencyID' => 'USD',
       'invoiceID' => $this->_invoiceID,