high

Cannot find module './Component'

Jest could not resolve a module import. The file may not exist, the path may be wrong, or the module resolution config may be misconfigured.

Common Causes

  1. 1File path is incorrect or has a typo
  2. 2Path aliases (e.g., @/) are not configured in Jest
  3. 3File extension is missing and not in the resolve list
  4. 4Module is not installed (missing from node_modules)
  5. 5Jest's moduleNameMapper config doesn't match your bundler's aliases

How to Fix

Configure moduleNameMapper for path aliases

// jest.config.ts
export default {
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
    '\\.(css|less|scss)$': 'identity-obj-proxy',
  },
};

Map path aliases to their actual paths so Jest can resolve imports the same way your bundler does.

Add moduleFileExtensions

// jest.config.ts
export default {
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json'],
};

Tell Jest which file extensions to try when resolving imports without explicit extensions.

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Related Errors

SyntaxError: Unexpected token

Jest encountered syntax it cannot parse. This usually means a file needs to be transformed (e.g., TypeScript, JSX, ESM) but the transformer is not configured.

Jest: Failed to transform file

Jest's transformer (Babel, ts-jest, SWC) failed to process a file. The transformer may be misconfigured or the file contains unsupported syntax.

Snapshot mismatch — expected value to match snapshot

The rendered output does not match the stored snapshot. The component output changed since the snapshot was last updated.

Timeout — Async callback was not invoked within 5000ms

An async test did not complete within the default 5-second timeout. The async operation may be hanging, or done() was never called.

UnhandledPromiseRejectionWarning

A Promise was rejected but no .catch() handler or try/catch block caught the error. This can cause flaky tests or missed failures.