Stack kata steps

stack_kata_steps.txt

# newly created stacks should be empty
# after one push stack size should be one
# after one push and one pop should be empty
# when pushed past limit stack overflows
# when empty stack popped should throw underflow
# when one is pushed one is popped
# when one and two are pushed two and one are popped
# when creating stack with negative size should throw illegal capacity
# when creating stack with zero capacity any push should overflow
# when one is pushed one is on top
# when stack is empty top throws empty
# with zero capacity stack top throws empty
# given stack with 1, 2 pushed find 1 and 2
# given stack with no 2, find should return nil