Summary

Fred Hebert shifts the unit of testing from an example to an invariant: instead of asserting what a function returns for one specific input, PropEr generates hundreds of random inputs and checks that a property holds for all of them, then shrinks any failing case down to the smallest input that still breaks it. Built around Erlang and Elixir, the book moves from writing basic properties and custom generators through targeted and stateful property testing, closing with a case study that models a book lending system as a finite state machine and tests it against that model. The shrinking mechanism is the book's throughline: it's what turns a random failing input into a minimal, debuggable one.

Target Readers

• Erlang and Elixir developers who write example-based tests and want to find edge cases their examples don't cover
• Engineers testing stateful systems who need a model-based approach beyond asserting individual input-output pairs
• Developers curious about property-based testing's core mechanism, generation and shrinking, who want it taught with a real language rather than in the abstract

Colophon

Publisher

ラムダノート

ISBN

978-4908686184

Published

Nov 2023

List price

¥4,950incl. taxMay differ from the actual selling price on Amazon