jest-setup-dom-matchers

What problem does it solve?

This Skill fixes the common Jest configuration mistake where @testing-library/jest-dom is loaded too early, causing custom matchers like toHaveAttribute, toHaveClass, and toHaveStyle to fail at runtime.

Core Features & Use Cases

• Root Cause Diagnosis: Identifies when Jest matchers are missing because setup code ran before expect was initialized.
• Correct Setup Separation: Recommends splitting pre-framework mocks and post-framework matcher registration into different setup files.
• Practical Verification: Helps confirm the fix by running a test that uses jest-dom matchers after the config change.
• Use Case: A React project has passing installs but failing tests with “is not a function” errors for DOM matchers; this Skill guides the exact configuration correction.

Quick Start

Update your Jest configuration so that pre-framework mocks stay in setupFiles and @testing-library/jest-dom is loaded from setupFilesAfterEnv.