Side-by-side comparison

Flexible, long-standing Node.js test framework usually paired with Chai and Sinon; common in older codebases.

Vite-native test runner with a Jest-compatible API and real-browser mode; the default for new projects.

Long-standing JavaScript test runner with snapshots and mocking; still huge, though Vitest wins new projects.

BDD/TDD assertion library (expect, should, assert) used with Mocha and bundled into Vitest.