@Test
void discoverUnaryDiscardEmptyColumns() throws Exception {

  configuration.setProcessEmptyColumns(false);
  unarySQL.execute(configuration);
  verify(resultReceiver, atLeastOnce()).receiveResult(ind.capture());
  assertThat(ind.getAllValues())
      .hasSize(1)
      .first()
      .isEqualTo(validInd());
}