Summary Fields v. 4.0.2 CiviCRM v. 5.16.3 Drupal 7
Our solution is clear - remove the test transactions. Also, end users won't have any test contributions so it won't be a problem for reporting for them.
However, Summary Fields seem to be including contributions that are marked as test - for instance, test event registrations. On the contribution tab, they are clearly marked as "Financial Type (test)".