toBeCloseTo equivalent for recursive equality test in Jest

Question

I have two objects and I want to test a recursive equality using Jest. This is pretty simple:

test('should be recursively equal', () => {
  const test = { x: 0, y: 0 }
  const expected = { x: 0, y: 0 }

  expect(test).toEqual(expected)
})

But there is a problem in some cases; as you know, JavaScript is pretty bad to compute float numbers, so sometimes the test becomes the following:

test('should be recursively equal', () => {
  const test = { x: 0.00000000001, y: 0 }
  const expected = { x: 0, y: 0 }

  expect(test).toEqual(expected)
})

And it does not work anymore. Jest provides the toBeCloseTo test, which takes a number and a precision as parameters, but I would like to know if there is an equivalent for recursive equalities (something like toEqualCloseTo).

Answer 1

I ended up with the following solution:

expect.extend({
  toEqualCloseTo(received, expected, precision = 3) {
    const { getType } = this.utils

    function round(obj) {
      switch (getType(obj)) {
      case 'array':
        return obj.map(round)

      case 'object':
        return Object.keys(obj).reduce((acc, key) => {
          acc[key] = round(obj[key])
          return acc
        }, {})

      case 'number':
        return +obj.toFixed(precision)

      default:
        return obj
      }
    }

    expect(round(received)).toEqual(expected)

    return { pass: true }
  },
})