jest

Installation
SKILL.md

Based on Jest Roblox v3.x, generated 2026-02-07.

Jest Roblox is a Luau port of Jest for the Roblox platform. It closely follows the upstream Jest API but has critical deviations due to Luau language constraints.

Critical deviations from JS Jest:

  • .never instead of .not (reserved keyword)
  • jest.fn() returns two values: mock object + forwarding function
  • 0, "", {} are truthy in Luau (only false and nil are falsy)
  • All globals (describe, expect, jest, etc.) must be explicitly imported
  • .each uses table syntax, not tagged template literals
  • Custom matchers take self as first parameter

Read core-deviations first when working with this codebase.

Core References

Related skills
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Apr 1, 2026