Unit Testing 05. String Builder

describe('StringBuilder', function() {
     it('Simple input test', function () {
        let str = new StringBuilder('hello');
         str.append(', there');
         str.prepend('User, ');
        str.insertAt('woop', 5);
         str.remove(6, 3);

        expect(str.toString()).equal('User,w hello, there');
     })

    it('Should throw error if not string input', function(){
         expect(() => new StringBuilder(2)).to.throw();
         let str = new StringBuilder('asd');
        expect(() => str.append(234)).to.throw();
    })

     it('Should have instance type', function(){
         expect(StringBuilder.prototype).to.have.property('append');
         expect(StringBuilder.prototype).to.have.property('prepend');
         expect(StringBuilder.prototype).to.have.property('insertAt');
         expect(StringBuilder.prototype).to.have.property('remove');
         expect(StringBuilder.prototype).to.have.property('toString');
    })
 })