vrandom/tests/uppercaseLetter.test.js

an easy way to work with random numbers in javascript

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

describe('uppercase letter', () => {
  it('should return a random uppercase letter', () => {
    const upperAlphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    const letter = uppercaseLetter()

    expect(upperAlphabet.includes(letter)).toBe(true)
  })

  it.each([
    { mockValue: 0.03842307692307692, expected: 'A' },
    { mockValue: 0.07684615384615384, expected: 'B' },
    { mockValue: 0.11526923076923076, expected: 'C' },
    { mockValue: 0.15369230769230768, expected: 'D' },
    { mockValue: 0.1921153846153846, expected: 'E' },
    { mockValue: 0.23053846153846153, expected: 'F' },
    { mockValue: 0.2689615384615385, expected: 'G' },
    { mockValue: 0.30738461538461537, expected: 'H' },
    { mockValue: 0.34580769230769226, expected: 'I' },
    { mockValue: 0.3842307692307692, expected: 'J' },
    { mockValue: 0.42265384615384616, expected: 'K' },
    { mockValue: 0.46107692307692305, expected: 'L' },
    { mockValue: 0.49949999999999994, expected: 'M' },
    { mockValue: 0.537923076923077, expected: 'N' },
    { mockValue: 0.5763461538461538, expected: 'O' },
    { mockValue: 0.6147692307692307, expected: 'P' },
    { mockValue: 0.6531923076923076, expected: 'Q' },
    { mockValue: 0.6916153846153845, expected: 'R' },
    { mockValue: 0.7300384615384615, expected: 'S' },
    { mockValue: 0.7684615384615384, expected: 'T' },
    { mockValue: 0.8068846153846153, expected: 'U' },
    { mockValue: 0.8453076923076923, expected: 'V' },
    { mockValue: 0.8837307692307692, expected: 'W' },
    { mockValue: 0.9221538461538461, expected: 'X' },
    { mockValue: 0.960576923076923, expected: 'Y' },
    { mockValue: 0.9989999999999999, expected: 'Z' }
  ])("uppercaseLetter() should return '$expected` when Math.random() returns $mockValue", ({ mockValue, expected }) => {
    jest.spyOn(Math, 'random').mockReturnValueOnce(mockValue)
    const actual = uppercaseLetter()

    expect(actual).toBe(expected)

    Math.random.mockRestore()
  })

  it('returns a string', () => {
    const actual = uppercaseLetter()

    expect(typeof actual).toBe('string')
  })

  it('returns a string of length 1', () => {
    const actual = uppercaseLetter()

    expect(actual.length).toBe(1)
  })
})