vrandom/tests/string.test.js

an easy way to work with random numbers in javascript

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

describe('string', () => {
  it('throws an error when called without arguments', () => {
    expect(() => string()).toThrow(TypeError("First argument 'size' needs to be an integer"))
  })

  it('throws an error when called with argument size < 1', () => {
    expect(() => string(-1)).toThrow(Error("First argument 'size' needs to be a positive integer ( size > 0)"))
  })

  it('throws an error when called with an invalid charset argument', () => {
    expect(() => string(5, 'hello')).toThrow(Error("Invalid charset 'hello' picked"))
  })

  it.each([{ size: 1 }, { size: 3 }, { size: 5 }, { size: 10 }, { size: 100 }, { size: 250 }, { size: 1000 }])(
    'string($size) should return a string of length $size',
    ({ size }) => {
      const actual = string(size)
      expect(typeof actual).toBe('string')
      expect(actual.length).toBe(size)
    }
  )

  it.each([
    { size: 5, mockValues: [0.1, 0.4, 0.5, 0.6, 0.9], expected: 'gyFL3' },
    { size: 3, mockValues: [0.99922, 0.85126, 0.00124], expected: '90a' }
  ])(
    "string($size) should return '$expected' when Math.random returns $mockValues individually",
    ({ size, mockValues, expected }) => {
      jest.spyOn(Math, 'random')
      mockValues.forEach(mockValue => {
        Math.random.mockReturnValueOnce(mockValue)
      })

      const actual = string(size)
      expect(actual).toBe(expected)

      Math.random.mockRestore()
    }
  )

  it.each([
    { size: 5, charset: 'alphanumeric', mockValues: [0.1, 0.4, 0.5, 0.6, 0.9], expected: 'gyFL3' },
    { size: 5, charset: 'alphabetic', mockValues: [0.1, 0.4, 0.5, 0.6, 0.9], expected: 'fuAFU' },
    { size: 3, charset: 'alphanumeric', mockValues: [0.99922, 0.85126, 0.00124], expected: '90a' },
    { size: 3, charset: 'alphabetic', mockValues: [0.99922, 0.85126, 0.00124], expected: 'ZSa' }
  ])(
    "string($size, '$charset') should return '$expected' when Math.random returns $mockValues individually",
    ({ size, charset, mockValues, expected }) => {
      jest.spyOn(Math, 'random')
      mockValues.forEach(mockValue => {
        Math.random.mockReturnValueOnce(mockValue)
      })

      const actual = string(size, charset)
      expect(actual).toBe(expected)

      Math.random.mockRestore()
    }
  )
})