describe('Add and subtract', () => {

    it('Should contain add, subtract, get', () => {

        let returnValue = createCalculator();

        expect(returnValue).to.haveOwnProperty('add');

        expect(returnValue).to.haveOwnProperty('subtract');

        expect(returnValue).to.haveOwnProperty('get');

    });


    it('Should not take any parameters', () => {

        let obj = createCalculator();

        obj.add(5);

        obj.subtract(3);

        let returnValue = obj.get();

        expect(returnValue).to.equal(2);

    });


    it('Should be a number', () => {

        let obj = createCalculator();

        obj.add('sss');

        let returnValue = obj.get();

        expect(returnValue).to.be.NaN;

    });


    it('Should parse this - "12"', () => {

        let obj = createCalculator();

        obj.add('8');

        obj.subtract('5');

        let returnValue = obj.get();

        expect(returnValue).to.equal(3);

    });


    it('Should work with different input', () => {

        let obj = createCalculator();

        obj.add(8);

        obj.subtract('5');

        let returnValue = obj.get();

        expect(returnValue).to.equal(3);

    });


    it('Should be a number', () => {

        let obj = createCalculator();

        obj.subtract('dssa');

        let returnValue = obj.get();

        expect(returnValue).to.be.NaN;

    });


});