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Cloud & DevOps · Tool

Jest

Confidence through automated tests.

Used at
  • Claro
01Overview

Jest is a JavaScript testing framework with a great developer experience. Automated testing is one of the fundamentals I never trade off — including when code is written with AI assistance.

02Key concepts

What anyone working with it needs to understand

  1. 01

    Test structure

    describe, it and arrange-act-assert.

  2. 02

    Matchers

    Expressive assertions for values, objects and errors.

  3. 03

    Mocks & spies

    Isolating units and controlling dependencies.

  4. 04

    Async testing

    Testing Promises, timers and async flows.

  5. 05

    Coverage

    Measuring coverage without chasing vanity metrics.

  6. 06

    Component testing

    Pairing with Testing Library to test UI behavior.

03In practice
Wrote Jest unit tests for logged-in area features at Claro, and enforce automated testing as an architecture standard today.
04Related