LEARN JAVASCRIPT UNIT TESTING Factorial Feature

index.js

const Calculate = {
  factorial: (inputValue) => {
    if (inputValue === 0) {return 1}
    else if (inputValue > 0) {
      let result = 1
      for(let i = 1; i <= inputValue; i++) {
        result *= i
      }
      return result
    }
    else {
      throw new Error("Error")
    }
  }
}

module.exports = Calculate;

index_test.js

var assert = require("assert");
var Calculate =  require('../index.js')

describe('Calculate', () => {
  describe('.factorial', () => {
    it("returns 120 for 5!", () => {
      const expectedResult = 120
      const inputValue = 5

      const result = Calculate.factorial(inputValue)
      assert.equal(result, expectedResult)
    })

    it('returns 6 for 3!', () => {
      const expectedResult = 6
      const inputValue = 3

      const result = Calculate.factorial(inputValue)
      assert.equal(result, expectedResult)
    })

    it('returns 1 for 0!', () => {
      const expectedResult = 1
      const inputValue = 0

      const result = Calculate.factorial(inputValue)
      assert.equal(result, expectedResult)
    })

  });
});