jest-unit.js

describe('formatNumber function', () => {
  it('works with strings', () => {
    const formatted = formatNumber('12.45')

    expect(formatted).toEqual('12,45')
  })

  it('works with numbers', () => {
    const formatted = formatNumber(12.45)

    expect(formatted).toEqual('12,45')
  })

  it('returns only 2 decimal places', () => {
    const formatted = formatNumber(12.1111)

    expect(formatted).toEqual('12,11')
  })

  it('rounds decimals right', () => {
    expect(formatNumber(12.665)).toEqual('12,67')
    expect(formatNumber(12.664)).toEqual('12,66')
  })
})