Add a failing test for Pizza::Topping.initialize.
overwrite initialize method for Topping class and set attr_accessor for name
add failing test for vegetarian topping
Add vegetarian keyword argument to Topping.intialize and add vegetarian keyword to attr_accessor
Add failing test for the non-existant topping method in the Pie class
Override intitialize method for Pie class to add topping instance variable. Set attr_accessor for toppings.
Add our own single topping test! Success!
Add failing test for when there are no arguments for new pie
Set default toppings in intitialize in the Pie class to be cheese