func testForEachMessage(mbox store.Folder, lowID, highID, suffix, expectedCount uint64, t *testing.T) { counter := uint64(0) err := mbox.ForEachMessage(lowID, highID, suffix, func(index, suffix uint64, msg []byte) error { counter++ return nil }) if err != nil { t.Errorf("For lowID %d, highID %d, suffix %d, got error %v", lowID, highID, suffix, err) } if expectedCount != counter { t.Errorf("For lowID %d, highID %d, suffix %d, expected counter %d got %d", lowID, highID, suffix, expectedCount, counter) } }