Writing bulletproof code with property-based testing
summary
Shows how property-based tests replace hand-picked cases with 1,000 semi-random examples by default and catches bugs missed by examples (uppercase-regex error found). Demonstrates jqwik and Kotest, jqwik’s shrinking to a minimal counterexample and seed-based reproducibility, and builds a stateful test for a text editor that simulates random sequences of edits/undo/redo (limits: 20 undos) to verify invariants. Notes tradeoffs: harder to find properties and slower runs, best for utility logic and edge-case coverage.
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chapters (11)
- 0:00Introduction to testing
- 1:56Example based testing explained
- 8:04Problems with example tests
- 9:05Property based testing intro
- 13:21Choosing a PBT framework
- 14:03Writing first property test
- 16:31Understanding jQuick reports
- 20:03Edge cases and shrinking
- 21:49Stateful testing explained
- 31:09Pros and cons of PBT
- 39:23When to use property tests
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