| accumulate | Split-Apply-Combine with Collapsing Groups | 
| csh_from_digits | Derive collapsing scheme from a hierarchical classification | 
| cumulate | Split-Apply-Combine with Collapsing Groups | 
| frac_complete | Demand minimal fraction of complete records | 
| from_validator | Use a validate::validator object to define a test | 
| min_complete | Demand minimal number of complete records | 
| min_records | Demand minimal number of records | 
| producers | Synthetic data on producers | 
| smoke_test | Check your testing function against common edge cases |