Issue #34: Add behat test for listing no role users

Author: buntybuddyboss

features/user-list.feature

@@ -26,3 +26,16 @@ Feature: List WordPress users
       """
       bobjones
       """
+
+  Scenario: List users without roles
+    Given a WP install
+    When I run `wp user generate --count=1 --format=ids`
+    Then save STDOUT as {USER_ID}
+
+    And I run `wp user remove-role {USER_ID} subscriber`
+
+    When I run `wp user list --role=none --field=id`
+    Then STDOUT should be:
+      """
+      {USER_ID}
+      """