Introduction to Shrinking

Shrinking

A critical component of property-based testing is shrinking. Shrinking is the mechanism by which a property-based testing framework can be told how to simplify failure cases enough to let us figure out exactly what the minimal reproducible case is. While finding complex obtuse cases is worthwhile, being able to reduce failing inputs to a simple counterexample truly is the killer feature.

But there are some cases where PropEr can’t do what we need. Either it can’t shrink large data structures well enough to be understandable, or ...