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0020, Vitest as the default test stack

Why every Olympus repo uses Vitest as its primary test runner

Status: Accepted Date: 2026-02 Stakeholders: Bobby Nannier

Context

Olympus repos are TypeScript-first. The test ecosystem options:

  • Jest, battle-tested, widely known, slow startup, awkward ESM/TS config.
  • Mocha + Chai, old guard, lots of config.
  • Node test runner (node:test), native, fast, but younger ecosystem.
  • Bun test, fast, native to Bun, but only works under Bun (not Node).
  • Vitest, modern, Vite-powered, fast, jest-compatible API, native ESM/TS.

Decision

Vitest in every Olympus repo: athena, hera, site, canvas, sdk, octl.

Consequences

  • Fast. Test startup is 10× faster than Jest's, especially noticeable on large suites.
  • Compatible. describe/it/expect works exactly like Jest.
  • Native ESM/TS. No babel config, no ts-jest. Just point at .ts files.
  • Watch mode is fast. Re-runs affected tests on save.
  • Coverage built-in via --coverage (uses V8 by default).
  • Single runner. Same shape across every repo lowers cognitive load.

End-to-end testing

For browser-based tests, Playwright complements Vitest. See Develop, Testing strategy.

0019, PKCE mandatory for all public clients

Why Olympus rejects authorization-code flows without PKCE for public clients

0021, xterm.js secrets sanitizer in Daedalus

How Daedalus prevents accidentally surfacing secrets to operators

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ContextDecisionConsequencesEnd-to-end testingRelated