Question

Write Mocha tests to check the functionality of the following JS code:

function sum(arr) {
    let sum = 0;
    for (let i of arr) {
        sum += Number(i);
    }
    return sum;
}

console.log(sum([3, 4, 5, 6, 7]));

Your tests will be supplied a function named 'sum'. It needs to meet the following requirements:

• Takes and array of numbers as argument
• Returns the sum of the values of all elements inside the array

Answer 1

Here is my solution:

let sum = require('../P04 SumOfNumbers').sum;
let expect = require("chai").expect;


describe('Sum of Numbers tests', () => {
    describe('General tests', () => {
        it('should be a function', () => {
            expect(typeof sum).to.equal('function');            
        });
    });

    describe('Function tests', () => {
        it('should return zero for a zero length input array', () => {
            expect(sum([])).to.equal(0);            
        });

        it('should return the member value for a one member array', () => {
            expect(sum([1])).to.equal(1);            
        });

        it('should return the member value for a one member array when given as string', () => {
            expect(sum(['1'])).to.equal(1);            
        });

        it('should add whole number arrays', () => {
            expect(sum([1,2,3])).to.equal(6);            
        });

        it('should add whole number arrays including negative numbers', () => {
            expect(sum([-1,2,3])).to.equal(4);            
        });

        it('should add whole number arrays including strings', () => {
            expect(sum([-1,'2',3])).to.equal(4);            
        });

        it('should add fractions', () => {
            expect(sum([1.1,2.2,3])).to.be.closeTo(6.3,0.0001);            
        });

        //it('should not add non-arrays', () => {
        //    expect(sum(1,2,3)).to.be.NaN;           
        //}); 

        it('should not add arrays of invalid data', () => {
            expect(sum(['pesho','gosho'])).to.be.NaN;           
        });
    });
});