Simple stack in Python

stack.py

# Author: Michelle Mackie
#
# Copyright (C) Summer 2012
# School of Computer Science
# Carnegie Mellon University
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation; either version 2 of the License,
# or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.
#
# For additional information visit http://www.andrew.cmu.edu/~icaoberg or
# send email to icaoberg@cmu.edu

#This defines a simple stack in Python 
#adapted from https://gist.github.com/2871311

class Stack:
  def __init__(self):
    self.stack = list()
	
  def push(self, value):
    if value == None:
      return False
    else:
      self.stack.insert(0, value)
    return True
	
  def peek(self):
    return self.stack[0]
	
  def pop(self):
    if self.stack:
      self.stack.pop(0)
      return True
    else:
      return False
	
  def size(self):
    return len(self.stack)
	
  def has(self, value):
    if value in self.stack:
      return True
    else:
      return False
	
   def clear(self):
     self.stack = list()

test.py

# Author: Michelle Mackie
#
# Copyright (C) Summer 2012
# School of Computer Science
# Carnegie Mellon University
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation; either version 2 of the License,
# or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.
#
# For additional information visit http://www.andrew.cmu.edu/~icaoberg or
# send email to icaoberg@cmu.edu

#Simple unit tests for the simple stack 

import stack
import unittest

class TestStack(unittest.TestCase):
  def testPush(self):
    s = stack.Stack()
    for value in range(1,101):
      self.assertEqual(True, s.push(value))
		
  def testPop(self):
    s = stack.Stack()
    for value in range(1, 11):
      self.assertEqual(True, s.push(value))
      self.assertEqual(True, s.pop())
		
    self.assertEqual(False, s.pop())
	
  def testPeek(self):
    s = stack.Stack()
    for value in range(1, 11):
      self.assertEqual(True, s.push(value))
      self.assertEqual(value, s.peek())
	
  def testHas(self):
    s = stack.Stack()
    for value in range(1, 11):
      self.assertEqual(True, s.push(value))
      self.assertEqual(True, s.has(value))
      self.assertEqual(False, s.has(value+1))
	
  def testSize(self):
    s = stack.Stack()
    for value in range(1, 11):
      self.assertEqual(True, s.push(value))
      self.assertEqual(value, s.size())
      self.assertEqual(False, s.has(value+1))
	
  def testClear(self):
    s = stack.Stack()
    for value in range(1, 11):
      self.assertEqual(True, s.push(value))
	
    self.assertEqual(10, s.size())
    s.clear()
    self.assertEqual(0, s.size())

if __name__ == '__main__':
        unittest.main()