jest TypeError: expect(...).toBeInTheDocument is not a function - setup file missing in CI

TL;DR

The toBeInTheDocument matcher is registered by @testing-library/jest-dom, which loads through a setup file wired into the jest config. When CI uses a different jest config than local runs, a common monorepo accident, the setup file never loads and every jest-dom matcher is undefined. Find the exact config CI invokes, verify its setupFilesAfterEnv entry points at a file that imports jest-dom, and rerun a single test file to confirm.

The query

jest TypeError: expect(...).toBeInTheDocument is not a function  -  setup file missing in CI

Use this when

• expect(...).toBeInTheDocument is not a function fails only in CI
• other jest-dom matchers (toHaveTextContent, toBeDisabled) fail the same way
• the repo is a monorepo with more than one jest config

Not for

• the matchers fail locally too (the package is not installed, or the setup file is missing everywhere)
• TypeScript complains about the matcher types but jest runs fine (a types problem, add the jest-dom types)
• the error is expect is not defined (the test environment itself is wrong)

Steps

1. Confirm which jest config the CI job actually uses

Read the test script in package.json and any --config flag. In monorepos, the CI job may run from a package directory with its own config that shadows the root one.

grep -A5 '"test"' package.json
ls jest.config.* packages/*/jest.config.* 2>/dev/null

Expected output: you know the exact config file CI loads, and whether a second config shadows it.

2. Check the setupFilesAfterEnv entry and the path it points to

Open that config and confirm the setup key exists and the file path resolves from the config's directory.

// jest.config.js
module.exports = {
  testEnvironment: 'jsdom',
  setupFilesAfterEnv: ['[rootDir]/jest.setup.js'],
};

Expected output: the entry is present and the path matches the real file location relative to the config.

3. Verify the setup file actually imports jest-dom

A setup file that exists but never imports the matchers produces exactly this error. One line is all it needs.

// jest.setup.js
import '@testing-library/jest-dom';

Expected output: the import is present; a missing import is fixed by adding it.

4. Rerun one failing test file in the CI environment

Run a single spec with the CI config to confirm the matchers register before running the whole suite.

npx jest src/components/Button.test.js --ci

Expected output: toBeInTheDocument resolves and the spec passes.

Tool compatibility

• jest 26 - 30
• @testing-library/jest-dom 5 - 6
• jsdom test environment

Variant phrasings

• toBeInTheDocument is not a function in CI
• TypeError: expect(...).toHaveTextContent is not a function
• jest-dom matchers undefined on CI but work locally

Why it happens

Jest only knows the custom matchers if the setup file runs, and it only runs the setup file listed in the config it loads. Monorepos and CI-specific configs (a --config flag, a per-package config, or config shadowing) break this chain silently: jest starts, the setup file is skipped, and the first jest-dom assertion throws. Local runs use the root config where everything is wired, so nobody notices until CI.

Edge cases / pitfalls

• setupFiles runs before the test framework is installed, setupFilesAfterEnv runs after: matchers must go in setupFilesAfterEnv
• with pnpm, @testing-library/jest-dom must be a declared dependency of the package whose config references it, or the import fails in CI's strict node_modules layout
• an ESM setup file with a CJS jest config (or vice versa) fails to load; keep the module systems consistent
• create-react-app and next/jest manage this wiring for you; ejecting or overriding their config can drop the setup file

Provenance

Resolved from the public thread: https://vectle.com/posts/pst__lVLjo61EU6IKGnOXN3PWw