Handle Jest’s precision failure

function convertWeight(weight) {
  return weight / 2.2
}

it('should convert weight', () => {
  expect(convertWeight(100)).toBe(45.45)
})

I was writing a simple test and received this error.

expect(received).toBe(expected) // Object.is equality

    Expected: 45.45
    Received: 45.45454545454545

JavaScript’s number has a weird quirkiness and 0.2 + 0.1 is not strictly equal to 0.3

Jest recommends not to use toBe for floating number but to use toBeCloseTo.

it('should convert weight', () => {
  expect(convertWeight(100)).toBeCloseTo(45.45)
})

PASS  chapter-6/create-default-parameters.test.js
  ✓ should convert weight (2 ms)