vrandom/tests/letter.test.js

an easy way to work with random numbers in javascript

const letter = require('../lib/letter.js')

describe('letter', () => {
  it.each([
    { mockValue: 0.0001, expected: 'a' },
    { mockValue: 0.999, expected: 'Z' },
    { mockValue: 0.5, expected: 'A' },
    { mockValue: 0.4879, expected: 'z' }
  ])("letter() should return '$expected` when Math.random() returns $mockValue", ({ mockValue, expected }) => {
    jest.spyOn(Math, 'random').mockReturnValueOnce(mockValue)
    const actual = letter()
    expect(actual).toBe(expected)

    Math.random.mockRestore()
  })

  it('returns a string', () => {
    const actual = letter()
    expect(typeof actual).toBe('string')
  })

  it('returns a string of lenght 1', () => {
    const actual = letter()
    expect(actual.length).toBe(1)
  })
})