text: describe("Stack", function() {
  
      var stack;
      beforeEach(function() {
          stack = new Stack();
      });
  
      it("can be pushed and popped", function() {
  	stack.push(1);
  	stack.push(2);
  	
  	expect(stack.peek()).toEqual(2);
  	expect(stack.pop()).toEqual(2);
  
  	expect(stack.peek()).toEqual(1);
  	expect(stack.pop()).toEqual(1);
  
  	expect(stack.peek()).toEqual(undefined);
  
  	expect(function() {
  	    stack.pop();
  	}).toThrow("empty");
      });
  
  });
  