#+LaTeX_CLASS: beamer
#+LaTeX_CLASS_OPTIONS: [presentation]
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#+LaTeX_HEADER: \usepackage[english]{babel} \usepackage{ae,aecompl}
#+LaTeX_HEADER: \usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet}

#+LaTeX_HEADER: \usepackage{listings}

#+LaTeX_HEADER:\lstset{language=Python, basicstyle=\ttfamily\bfseries,
#+LaTeX_HEADER:  commentstyle=\color{red}\itshape, stringstyle=\color{red},
#+LaTeX_HEADER:  showstringspaces=false, keywordstyle=\color{blue}\bfseries}

#+TITLE:     
#+AUTHOR:    FOSSEE
#+EMAIL:     
#+DATE:    

#+DESCRIPTION: 
#+KEYWORDS: 
#+LANGUAGE:  en
#+OPTIONS:   H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t
#+OPTIONS:   TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc

* 
#+begin_latex
\begin{center}
\vspace{12pt}
\textcolor{blue}{\huge Testing and Debugging}
\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_latex
* Objectives 
  At the end of the tutorial, you will be able to,

 - Understand what is software testing.
 - Test simple functions for their functionality.
 - Automate tests. 
 - Understand the need for coding style 
 - Learn  some of the standards followed by the Python Community.
 - Handle Errors and Exceptions.

* Pre-requisite
Spoken tutorial on -
- Getting started with functions.
- Advanced Features of functions.   
* gcd function
  - Create gcd.py file with:
#+begin_src python
  def gcd(a, b):
        if b == 0: 
            return b
        return gcd(b, a%b)
#+end_src python

* Test for gcd.py
  - Edit gcd.py file
#+begin_src python 
  def gcd(a, b):
      if b == 0:
          return a
      return gcd(b, a%b)
  
  if __name__=='__main__':
      result = gcd(48, 64)
      if result != 16:
          print "Test failed"
      print "Test Passed"

#+end_src

* Idiom
if \_\_name\_\_ == '\_\_main\_\_':
* Exercise 1
 - Write code for gcd and write tests for it  
* Structure of file
    |   12 |    28 |    4 |
    |   18 |    36 |   18 |
    | 4678 | 39763 | 2339 |
* Code piece
#+begin_src python
if __name__ == '__main__':
    for line in open('testcases.txt'):
        numbers = line.split()
        x = int(numbers[0])
        y = int(numbers[1])
        result = int(numbers[2])
    if gcd(x, y) != result:
        print "Failed gcd test for", x, y
    else:
        print "Test passed", result
#+end_src
* Exercise 2
- For the same inputs as gcd write automated tests for LCM.
* Solution 2
#+begin_src python
  def gcd(a, b):
      if a % b == 0: 
          return b
      return gcd(b, a%b)
  def lcm(a, b):
      return (a * b) / gcd(a, b)
  if __name__ == '__main__':
      for line in open('lcmtestcases.txt'):
          numbers = line.split()
          x = int(numbers[0])
          y = int(numbers[1])
          result = int(numbers[2])
       	  if lcm(x, y) != result:
              print "Failed lcm test for", x, y
          else:
              print "Test passed", result
#+end_src
* Meaning full names
#+begin_src python   
   
   amount = 12.68
   denom = 0.05
   nCoins = round(amount / denom)
   rAmount = nCoins * denom

#+end_src

* Code style
 - Four Space Indentation
 - 79 character limit on a line
 - Funtions should be seperated by 
   blank line
 - Use Docstring
 - White space around operators 
   - l = 32 % 4

* Exercise 3
   - Give meaningful names to the variables in following
     code
	
     - c = a / b

* Solution 3
#+begin_src python

  quotient = dividend / divisor

#+end_src

* Using idb
#+begin_latex
\small
\begin{lstlisting}
In []: import mymodule
In []: mymodule.test()
---------------------------------------------
NameError   Traceback (most recent call last)
<ipython console> in <module>()
mymodule.py in test()
      1 def test():
      2     total=1+1
----> 3     print spam
NameError: global name 'spam' is not defined

In []: %debug
> mymodule.py(2)test()
      0     print spam
ipdb> total
2
\end{lstlisting}

#+end_latex

* Summary
 In this tutorial, we have learnt to, 
 	
 - Create simple tests for a function.
 - Automate tests using many predefined test cases.
 - Use the python coding standards.
 - Differentiate between syntax error and exception.
 - Handle exception using ``try'' and ``except''.
 - Use ``%debug'' for debugging on ipython.

* Evaluation
1. What is proper indentation for python code according to style guidelines?

    - two space identation
    - three space identation
    - four Space Indentation
    - no Indentation 
   
2. How do you start the debugger on ipython?
    - debug
    - %debug
    - %debugger
    - start debugger
  
3. What is the idiom used for running python scripts in a standalone manner?
* Solutions
1. Four Space Indentation

2. %debug

3. if \_\_name\_\_ == '\_\_main\_\_':
* 
#+begin_latex
  \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_latex