Setup
caution
jest-extended
only supports Jest version 27.2.5
and newer. If you're using an older version of Jest, use 1.2.1
.
Create a setup script with the following:
testSetup.js
// add all jest-extended matchers
import * as matchers from 'jest-extended';
expect.extend(matchers);
// or just add specific matchers
import { toBeArray, toBeSealed } from 'jest-extended';
expect.extend({ toBeArray, toBeSealed });
Add your setup script to your Jest setupFilesAfterEnv
configuration. See for help
package.json
"jest": {
"setupFilesAfterEnv": ["./testSetup.js"]
}
To automatically extend expect
with all matchers, you can use
package.json
"jest": {
"setupFilesAfterEnv": ["jest-extended/all"]
}
Use with vitest
jest-extended
works with vitest
because their expect.extend
API is compatible. In your setup script:
testSetup.js
import { expect } from 'vitest';
import * as matchers from 'jest-extended';
expect.extend(matchers);
Add this setup script to your vitest.config.js
:
vitest.config.js
export default defineConfig({
test: {
setupFiles: ['./testSetup.js'],
},
});
Vitest TypeScript types setup
To use Vitest with TypeScript, create a file named jest-extended.d.ts
with the content below in addition to the setup above.
/// <reference types="vitest" />
export interface CustomMatchers<R> extends Record<string, any> {
toHaveBeenCalledAfter(
mock: jest.MockInstance<any, any[]> | import('vitest').MockInstance<any, any[]>,
failIfNoFirstInvocation?: boolean,
): R;
toHaveBeenCalledBefore(
mock: jest.MockInstance<any, any[]> | import('vitest').MockInstance<any, any[]>,
failIfNoSecondInvocation?: boolean,
): R;
toHaveBeenCalledExactlyOnceWith(...args: unknown[]): R;
}
For Vitest >= 0.31.0, append the content below to the new file.
declare module 'vitest' {
// eslint-disable-next-line @typescript-eslint/no-empty-interface
interface Assertion<T = any> extends CustomMatchers<T> {}
}
For Vitest < 0.31.0, append the content below to the new file.
declare namespace Vi {
// eslint-disable-next-line @typescript-eslint/no-empty-interface
interface AsymmetricMatchersContaining extends CustomMatchers<any> {}
}