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+\documentclass[12pt,presentation]{beamer}
+\usepackage[utf8]{inputenc}
+\usepackage[T1]{fontenc}
+\usepackage{fixltx2e}
+\usepackage{graphicx}
+\usepackage{longtable}
+\usepackage{float}
+\usepackage{wrapfig}
+\usepackage{soul}
+\usepackage{textcomp}
+\usepackage{marvosym}
+\usepackage{wasysym}
+\usepackage{latexsym}
+\usepackage{amssymb}
+\usepackage{hyperref}
+\tolerance=1000
+\usepackage[english]{babel} \usepackage{ae,aecompl}
+\usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet}
+\usepackage{listings}
+\lstset{language=Python, basicstyle=\ttfamily\bfseries,
+commentstyle=\color{red}\itshape, stringstyle=\color{green},
+showstringspaces=false, keywordstyle=\color{blue}\bfseries}
+\providecommand{\alert}[1]{\textbf{#1}}
+
+\title{Getting started with TDD}
+\author{FOSSEE}
+\institute{IIT Bombay}
+
+\usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent}
+
+\AtBeginSection[]
+{
+  \begin{frame}<beamer>
+    \frametitle{Outline}
+    \tableofcontents[currentsection]
+  \end{frame}
+}
+
+\begin{document}
+
+\begin{frame}
+
+\begin{center}
+\vspace{12pt}
+\textcolor{blue}{\huge Getting started with Test Driven Development}
+\end{center}
+\vspace{18pt}
+\begin{center}
+\vspace{10pt}
+\includegraphics[scale=0.95]{../../images/fossee-logo.png}\\
+\vspace{5pt}
+\scriptsize Developed by FOSSEE Team, IIT-Bombay. \\ 
+\scriptsize Funded by National Mission on Education through ICT\\
+\scriptsize  MHRD,Govt. of India\\
+\includegraphics[scale=0.30]{../../images/iitb-logo.png}\\
+\end{center}
+\end{frame}
+
+\begin{frame}
+\frametitle{Outline}
+\setcounter{tocdepth}{3}
+\tableofcontents
+\end{frame}
+
+\section{Introduction}
+
+\begin{frame}
+  \frametitle{Objectives}
+  At the end of this section, you will be able to:
+  \begin{itemize}
+  \item Understand the concept of Test Driven Development.
+  \item Write your code using the TDD paradigm.
+  \end{itemize}
+\end{frame}
+
+
+\begin{frame}
+\frametitle{Pre-requisite}
+\label{sec-3}
+
+Spoken tutorial on Basic Python
+\begin{itemize}
+\item Topic of tutorial here
+\end{itemize}
+\end{frame}
+
+
+\begin{frame}
+  \frametitle{What is TDD?}
+  The basic steps of TDD are roughly as follows --
+  \begin{enumerate}
+  \item Decide upon the feature to implement and the methodology of
+    testing it.
+  \item Write the tests for the feature decided upon.
+  \item Just write enough code, so that the test can be run, but it fails.
+  \item Improve the code, to just pass the test and at the same time
+    passing all previous tests.
+  \item Run the tests to see, that all of them run successfully.
+  \item Refactor the code you've just written -- optimize the algorithm,
+    remove duplication, add documentation, etc.
+  \item Run the tests again, to see that all the tests still pass.
+  \item Go back to 1.
+  \end{enumerate}
+\end{frame}
+
+\section{First Test}
+
+\begin{frame}[fragile]
+  \frametitle{First Test -- GCD}
+  \begin{itemize}
+  \item simple program -- GCD of two numbers
+  \item What are our code units?
+    \begin{itemize}
+    \item Only one function \texttt{gcd}
+    \item Takes two numbers as arguments
+    \item Returns one number, which is their GCD
+    \end{itemize}
+\begin{lstlisting}
+c = gcd(44, 23)
+\end{lstlisting}
+  \item c will contain the GCD of the two numbers.
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Test Cases}
+  \begin{itemize}
+  \item Important to have test cases and expected outputs even before
+    writing the first test!
+  \item $a=48$, $b=48$, $GCD=48$
+  \item $a=44$, $b=19$, $GCD=1$
+  \item Tests are just a series of assertions
+  \item True or False, depending on expected and actual behavior
+  \end{itemize}
+
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Test Cases -- Code}
+\begin{lstlisting}
+tc1 = gcd(48, 64)
+if tc1 != 16:
+    print "Failed for a=48, b=64. Expected 16. \
+    Obtained %d instead." % tc1
+    exit(1)
+
+tc2 = gcd(44, 19)
+if tc2 != 1:
+    print "Failed for a=44, b=19. Expected 1. \
+    Obtained %d instead." % tc2
+    exit(1)
+
+print "All tests passed!"
+\end{lstlisting}
+\begin{itemize}
+\item The function \texttt{gcd} doesn't even exist!
+\end{itemize}
+\end{frame}
+
+
+\begin{frame}[fragile]
+  \frametitle{Stubs}
+  \begin{itemize}
+  \item First write a very minimal definition of \texttt{gcd}
+    \begin{lstlisting}
+def gcd(a, b):
+    pass
+    \end{lstlisting}
+  \item Written just, so that the tests can run
+  \item Obviously, the tests are going to fail
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{\texttt{gcd.py}}
+\begin{lstlisting}
+def gcd(a, b):
+    pass
+
+if __name__ == '__main__':
+    tc1 = gcd(48, 64)
+    if tc1 != 16:
+        print "Failed for a=48 and b=64. \
+        Expected 16. Obtained %d instead." % tc1
+        exit(1)
+    tc2 = gcd(44, 19)
+    if tc2 != 1:
+        print "Failed for a=44 and b=19. \
+        Expected 1. Obtained %d instead." % tc2
+        exit(1)
+    print "All tests passed!"
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{First run}
+\begin{lstlisting}
+$ python gcd.py
+Traceback (most recent call last):
+  File "gcd.py", line 7, in <module> 
+  print "Failed for a=48 and b=64. Expected 16. 
+  Obtained %d instead." % tc1
+TypeError: %d format: 
+a number is required, not NoneType
+\end{lstlisting} %$
+
+  \begin{itemize}
+  \item We have our code unit stub, and a failing test. 
+  \item The next step is to write code, so that the test just passes.
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Euclidean Algorithm}
+  \begin{itemize}
+  \item Modify the \texttt{gcd} stub function
+  \item Then, run the script to see if the tests pass.
+  \end{itemize}
+\begin{lstlisting}
+def gcd(a, b):
+    if a == 0:
+        return b
+    while b != 0:
+        if a > b:
+            a = a - b
+        else:
+            b = b - a
+    return a
+\end{lstlisting}
+\begin{lstlisting}
+$ python gcd.py
+All tests passed!
+\end{lstlisting} %$
+  \begin{itemize}
+  \item \alert{Success!}
+  \end{itemize}
+\end{frame}
+
+
+\begin{frame}[fragile]
+  \frametitle{Euclidean Algorithm -- Modulo}
+  \begin{itemize}
+  \item Repeated subtraction can be replaced by a modulo
+  \item modulo of \texttt{a\%b} is always less than b
+  \item when \texttt{a < b}, \texttt{a\%b} equals \texttt{a}
+  \item Combine these two observations, and modify the code
+\begin{lstlisting}
+def gcd(a, b):
+    while b != 0:
+        a, b = b, a % b
+    return a
+\end{lstlisting}
+  \item Check that the tests pass again
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Euclidean Algorithm -- Recursive}
+  \begin{itemize}
+  \item Final improvement -- make \texttt{gcd} recursive
+  \item More readable and easier to understand
+\begin{lstlisting}
+def gcd(a, b):
+    if b == 0:
+        return a
+    return gcd(b, a%b)
+\end{lstlisting}
+  \item Check that the tests pass again
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Document \texttt{gcd}}
+  \begin{itemize}
+  \item Undocumented function is as good as unusable
+  \item Let's add a docstring \& We have our first test!
+  \end{itemize}
+\begin{lstlisting}
+def gcd(a, b):
+    """Returns the Greatest Common Divisor of the 
+    two integers passed as arguments.
+
+    Args:
+      a: an integer
+      b: another integer
+
+    Returns: Greatest Common Divisor of a and b
+    """
+    if b == 0:
+        return a
+    return gcd(b, a%b)
+\end{lstlisting}
+\end{frame}
+
+
+\begin{frame}[fragile]
+  \frametitle{Persistent Test Cases}
+  \begin{itemize}
+  \item Tests should be pre-determined and written, before the code
+  \item Test Data is repeatedly used; Hence, saved in persistent
+    format
+  \item Let's save data for GCD tests in a text file. 
+  \item The file shall have multiple lines of test data
+  \item Each line corresponds to a single test case
+  \item Each line consists of three comma separated values --
+    \begin{itemize}
+    \item First two coloumns are the integers for which the GCD has to be
+      computed
+    \item Third coloumn is the expected GCD to the preceding two
+      numbers.
+    \end{itemize}
+  \item Let us call our data file \texttt{gcd\_testcases.dat}
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Modify \texttt{gcd.py}}
+\begin{lstlisting}
+if __name__ == '__main__':
+    for line in open('gcd_testcases.dat'):
+        values = line.split(', ')
+        a = int(values[0])
+        b = int(values[1])
+        g = int(values[2])
+
+        tc = gcd(a, b)
+        if tc != g:
+            print "Failed for a=%d and b=%d.\
+            Expected %d. Obtained %d instead."\
+            % (a, b, g, tc)
+            exit(1)
+
+    print "All tests passed!"
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}
+
+  \begin{block}{}
+  \begin{center}
+  \textcolor{blue}{\Large THANK YOU!} 
+  \end{center}
+  \end{block}
+\begin{block}{}
+  \begin{center}
+    For more Information, visit our website\\
+    \url{http://fossee.in/}
+  \end{center}  
+  \end{block}
+\end{frame}
+
+\end{document}