Test-driven development

Stack.py

Class Stack():
  def __init__(self,size):
    self.size=size
    self.stack=[]
    self.top=-1
    
  def push(self,n):
    if self.isfull():
      print "Out of range"
    else:
      self.stack.append(n)
      self.top=self.top+1
  
  def pop(self):
    if self.isempty():
      print "Stack is empty"
    else:
      self.top=self.top-1
      return self.stack.pop()
  
  def isfull(self):
    return self.top+1==self.size
    
  def isempty(self):
    return self.top==-1
  

TDD

Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: first the developer writes an (initially failing) automated test case that defines a desired improvement or new function, then produces the minimum amount of code to pass that test, and finally refactors the new code to acceptable standards. Kent Beck, who is credited with having developed or 'rediscovered'[1] the technique, stated in 2003 that TDD encourages simple designs and inspires confidence.

A commonly applied structure for test cases has (1) setup, (2) execution, (3) validation, and (4) cleanup.

Stack test case:
1. s = Stack(10) print s.size
2. s.push(1)
3. s.isfull()
4. s.pop()
5. s.isempty()