Skip to contents

Construct a property-based test generator

Source: R/generator.R
new_generator.Rd

A generator draws a value together with an integrated tree of smaller values. new_generator() is the extension point for custom generators. Its draw function receives a non-negative integer size and returns one value. Its deterministic shrink function returns a list of strictly smaller values. The custom shrinker constructs that list itself; the framework constructs and transforms the corresponding tree nodes only as they are visited.

Usage

new_generator(
  draw,
  shrink = function(value) list(),
  label = "custom",
  prototype = list()
)

Arguments

draw

Function of one size argument that returns a value.

shrink

Function of one generated value that returns a list of smaller values.

label

Short description used in diagnostics.

prototype

Zero-length prototype used by gen_vector().

Value

An S7 generator object.