Jasmine expect toEqual but ignore additional properties on the actual object to prevent 'Expected … not to have properties …'

Question

Sometimes I need to assert only specific properties of the actual object and I don't care about the other properties.

For example:

const actual = [
  { a: 1, additionalProp: 'not interestig' },
  { a: 2, additionalProp: 'not interestig' }
];

expect(actual).toEqual([
  { a: 1 },
  { a: 2 }
])

This currently fails with:

Expected $[0] not to have properties
additionalProp: 'random value'

How can I write the expectation?

I currently do something like this:

expect(actual.map(i => ({a: 1}))).toEqual([
  { a: 1 },
  { a: 2 }
])

but I don't like it much and it does not work for more complex objects

Answer 1

You could explicitly address specific objects and their relevant attributes?

expect(actual.length).toBe(2);
expect(actual[0]['a']).toBe(1);
expect(actual[1]['a']).toBe(2);

Another approach is using jasmine.obectContaining . This may be more appropriate in case the expected objects contain several properties.

const expected = [
    { a: 1 },
    { a: 2 }
];
expect(actual.length).toBe(expected.length);
for (let i = 0; i < expected.length; i++) {
    expect(actual[i]).toEqual(jasmine.objectContaining(expected[i]));
}