π TDD, Where Did It All Go Wrong (Ian Cooper)
Overview
Ian Cooper's DevTernity talk revisits Kent Beck's original TDD ideas and shows where misunderstandings crept in. It argues tests should target behaviors through public interfaces rather than implementation details, so suites support refactoring instead of resisting it.
On Hacker News
HN repeatedly calls it the best talk on testing, and many say it changed how they approach tests, mocks and the meaning of a unit.
Topics
Sources
Video by DevTernity Conference, played through YouTube.
Data and selection notes
HN summaries and labels may contain AI errors. HN dates refer to discussions, not video publication.
HN Library: HackerTube export (2026-10-31) and open-index/hacker-news. Upstream summaries and classifications may contain AI errors.
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Selection checks
- SaaS & AI candidates: Topic keywords do not match
- Editor-approved picks: Editorial review is required
What people said