no-hooks.md

Disallow setup and teardown hooks (no-hooks)

Jest provides global functions for setup and teardown tasks, which are called before/after each test case and each test suite. The use of these hooks promotes shared state between tests.

Rule Details

This rule reports for the following function calls:

• beforeAll
• beforeEach
• afterAll
• afterEach

Examples of incorrect code for this rule:

/* eslint jest/no-hooks: "error" */

function setupFoo(options) {
  /* ... */
}

function setupBar(options) {
  /* ... */
}

describe('foo', () => {
  let foo;

  beforeEach(() => {
    foo = setupFoo();
  });

  afterEach(() => {
    foo = null;
  });

  it('does something', () => {
    expect(foo.doesSomething()).toBe(true);
  });

  describe('with bar', () => {
    let bar;

    beforeEach(() => {
      bar = setupBar();
    });

    afterEach(() => {
      bar = null;
    });

    it('does something with bar', () => {
      expect(foo.doesSomething(bar)).toBe(true);
    });
  });
});

Examples of correct code for this rule:

/* eslint jest/no-hooks: "error" */

function setupFoo(options) {
  /* ... */
}

function setupBar(options) {
  /* ... */
}

describe('foo', () => {
  it('does something', () => {
    const foo = setupFoo();
    expect(foo.doesSomething()).toBe(true);
  });

  it('does something with bar', () => {
    const foo = setupFoo();
    const bar = setupBar();
    expect(foo.doesSomething(bar)).toBe(true);
  });
});

Options

{
  "jest/no-hooks": [
    "error",
    {
      "allow": ["afterEach", "afterAll"]
    }
  ]
}

allow

This array option whitelists setup and teardown hooks so that this rule does not report their usage as being incorrect. There are four possible values:

• "beforeAll"
• "beforeEach"
• "afterAll"
• "afterEach"

By default, none of these options are enabled (the equivalent of { "allow": [] }).

Examples of incorrect code for the { "allow": ["afterEach"] } option:

/* eslint jest/no-hooks: ["error", { "allow": ["afterEach"] }] */

function setupFoo(options) {
  /* ... */
}

let foo;

beforeEach(() => {
  foo = setupFoo();
});

afterEach(() => {
  jest.resetModules();
});

test('foo does this', () => {
  // ...
});

test('foo does that', () => {
  // ...
});

Examples of correct code for the { "allow": ["afterEach"] } option:

/* eslint jest/no-hooks: ["error", { "allow": ["afterEach"] }] */

function setupFoo(options) {
  /* ... */
}

afterEach(() => {
  jest.resetModules();
});

test('foo does this', () => {
  const foo = setupFoo();
  // ...
});

test('foo does that', () => {
  const foo = setupFoo();
  // ...
});

When Not To Use It

If you prefer using the setup and teardown hooks provided by Jest, you can safely disable this rule.

Further Reading

• Jest docs - Setup and Teardown
• @jamiebuilds Twitter thread