Containing Only

arrayContainingOnly

An asymmetric matcher that checks if the received array contains only the expected values, using deep equality.

Values can be repeated (or omitted), but all elements should be present in the expected array.

note

Put another way, it checks that the received array is a subset of (or equal to) the expected array. This is in contrast to arrayContaining, which checks that the received array is a superset of (or equal to) the expected array.

it("contains only the expected values", () => {
  expect({ array: [1, 2] }).toEqual({
    array: expect.arrayContainingOnly([1, 2, 3]),
  });
  expect({ array: [1, 2] }).toEqual({
    array: expect.arrayContainingOnly([1, 2]),
  });
  expect({ array: [1, 1] }).toEqual({
    array: expect.arrayContainingOnly([1, 2, 2]),
  });
  
  expect({ array: [1, 2, 3] }).not.toEqual({
    array: expect.arrayContainingOnly([1, 2]),
  });
});

Tests

objectContainingOnly

An asymmetric matcher that checks if the received object contains only the expected keys and values, using deep equality.

Keys can be repeated (or omitted), but all keys should be present in the expected object.

note

Put another way, it checks that the received object is a subset of (or equal to) the expected object. This is in contrast to objectContaining, which checks that the received object is a superset of (or equal to) the expected object.

it("contains only the expected keys and values", () => {
  expect({ a: 1 }).toEqual(expect.objectContainingOnly({ a: 1, b: 2 }));
  expect({ a: 1, b: 2 }).toEqual(expect.objectContainingOnly({ a: 1, b: 2 }));

  expect({ a: 1, b: 2 }).not.toEqual(expect.objectContainingOnly({ a: 1 }));
});

Tests