Edit in JSFiddle

describe('Division by Zero', function () {
    // Setup (or Given)
    var number;
    beforeEach(function () {
        number = 10;
    });
    describe('when dividing a number by zero', function () {
        // Execute (or When)
        it('we get Infinity', function () {
            // Expect (or Then)
            expect(number/0).toEqual(Infinity);
        });
    });
});