def test_push_many():
"""
Can successfully push multiple nodes onto a stack
"""
fruits = Stack()
fruits.push('apple')
fruits.push('pear')
expected = 'pear'
assert expected == fruits.peek_stack()
def test_push_one():
"""
Can successfully push onto a stack
Can successfully peek the next item on the stack.
"""
fruits = Stack()
fruits.push('apple')
expected = 'apple'
assert expected == fruits.peek_stack()
def test_pop():
"""
Can successfully pop off the stack
Can successfully empty a stack after multiple pops.
"""
fruits = Stack()
fruits.push('apple')
fruits.push('pear')
fruits.pop()
fruits.pop()
assert 'No value.' == fruits.peek_stack()
def depth_first(self,node):
stack = Stack()
stack.push(node)
seen =[]
while stack.peek_stack() is not None:
current = stack.pop()
if current.visited == False:
seen.append(current.value)
current.visited = True
for i in current.list:
stack.push(i[0])
if current.visited is False:
stack.pop()
return seen
