mySizeTest

describe('mySize', function () {
    const testArr = [1,2,3,4] //This line modified from original test for readability
    const testObj = Object.assign({}, unmodifiedTestObj)

    it('correctly returns the size of the collection when an array is passed', function () {
      expect(mySize(testArr)).to.equal(testArr.length)
    })
...