AsymmetricMatchersBuiltin

interface AsymmetricMatchersBuiltin

• any(constructor: (...args: any[]) => any | new (...args: any[]) => any): any

  Matches anything that was created with the given constructor. You can use it inside toEqual or toBeCalledWith instead of a literal value.

  function randocall(fn) {
    return fn(Math.floor(Math.random() * 6 + 1));
  }
  
  test('randocall calls its callback with a number', () => {
    const mock = jest.fn();
    randocall(mock);
    expect(mock).toBeCalledWith(expect.any(Number));
  });
  
• anything(): any

  Matches anything but null or undefined. You can use it inside toEqual or toBeCalledWith instead of a literal value. For example, if you want to check that a mock function is called with a non-null argument:

  test('map calls its argument with a non-null argument', () => {
    const mock = jest.fn();
    [1].map(x => mock(x));
    expect(mock).toBeCalledWith(expect.anything());
  });
  
• arrayContaining<E = any>(arr: readonly E[]): any

  Matches any array made up entirely of elements in the provided array. You can use it inside toEqual or toBeCalledWith instead of a literal value.

  Optionally, you can provide a type for the elements via a generic.
• closeTo(num: number, numDigits?: number): any

  Useful when comparing floating point numbers in object properties or array item. If you need to compare a number, use .toBeCloseTo instead.

  The optional numDigits argument limits the number of digits to check after the decimal point. For the default value 2, the test criterion is Math.abs(expected - received) < 0.005 (that is, 10 ** -2 / 2).
• objectContaining(obj: object): any

  Matches any object that recursively matches the provided keys. This is often handy in conjunction with other asymmetric matchers.

  Optionally, you can provide a type for the object via a generic. This ensures that the object contains the desired structure.
• stringContaining(str: string | String): any

  Matches any received string that contains the exact expected string
• stringMatching(regex: string | String | RegExp): any

  Matches any string that contains the exact provided string