BITlab: Behavior Information Technology

404 Wilson Rd. Room 251
Communication Arts & Sciences
Michigan State University
East Lansing, MI 48824

Software Testing

Exercise: What is a bug?

Software testing is usually defined as the process of finding and eliminating bugs in software. Take a minute and write down your answer to the question “What is a bug?”

Why Test?

Test Cases and Automating Tests

A single, logical piece of functionality with well-defined inputs and expected outputs. It must be able to be exactly matched as “success” or “failure”.

Types of Tests


  1. In python (or your favorite language), write a “Fibonnaci” function that accepts an input n and prints out the first n fibonnaci numbers.
  2. Write a function that conducts a level 0 test.
  3. Write a set of functions that conduct as comprehensive set of level 1 tests.
  4. Write a set of functions taht conduct a set of level 2 tests.
  5. Write a function that measures the performance of your fibonnaci function (level 3 tests).

Fibonnaci code

def fib(n):
  if type(n) is not int:
    raise TypeError()
  if n <= 0:
    raise IndexError()
  if n <= 2:
    return 1
    return fib(n-2) + fib(n-1)

Example Test Code

import unittest
import datetime

from rick import fib

class TestFib(unittest.TestCase):

  # *** Level 0 tests ***
  def test_fib4(self):
    self.assertEqual(fib(4), 3)
  def test_fib5(self):
    self.assertEqual(fib(5), 5)
  # *** Level 1 tests ***
  def test_fib1(self):
    self.assertEqual(fib(1), 1)
  def test_fib2(self):
    self.assertEqual(fib(2), 1)

  def test_fib3(self):
    self.assertEqual(fib(3), 2)

  # *** Level 2 tests ***
  def test_fibneg5(self):
    self.assertRaises(IndexError, fib, -5)
  def test_fib0(self):
    self.assertRaises(IndexError, fib, 0)

  def test_fibhi(self):
    self.assertRaises(Exception, fib, "hi")
  def test_fib2str(self):
    self.assertRaises(Exception, fib, "2")

  def test_fib2point(self):
    self.assertRaises(Exception, fib, 2.0)
  def test_fib2point5(self):
    self.assertRaises(Exception, fib, 2.5)
  # *** Level 3 tests ***
  def test_fibperf(self):
    start =
    out = fib(40)
    end =
    self.assertLess((end-start).total_seconds(), 10)
if __name__ == '__main__':

Testing an Application


Choose an application you wrote recently. Write an integration test case – a script for a user going through a process, and the detailed output expected.

Developing Tests

Philosophical issues