JavaScript FizzBuzz

July 04, 2018

This blog assumes a global install of mocha, although that can also be installed locally. chai is also required as the assertion library - install as a dev dependency.

Writing tests

Create fizzbuzz.mocha.js.

const lib = require("./index")
const chai = require("chai")
const { expect } = chai
describe("check basic function", function() {
  it("should return when not part of fizz buzz", function() {
    const res = lib.run(2)
    expect(res).to.equal(2)
  })

  it("should return fizz", function() {
    const res = lib.run(3)
    expect(res).to.equal("Fizz")
  })

  it("should return buzz", function() {
    const res = lib.run(5)
    expect(res).to.equal("Buzz")
  })

  it("should return fizzbuzz", function() {
    const res = lib.run(15)
    expect(res).to.equal("FizzBuzz")
  })
})

Main js file

Create index.js:

const run = arg => {
  switch (true) {
    case arg % 15 === 0:
      return "FizzBuzz"
    case arg % 3 === 0:
      return "Fizz"
    case arg % 5 === 0:
      return "Buzz"
    default:
      return arg
  }
}

module.exports = {
  run,
}

Testing

Change into directory and run mocha fizzbuzz.mocha.js.

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