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#+LaTeX_HEADER:\lstset{language=Python, basicstyle=\ttfamily\bfseries,

#+LaTeX_HEADER:  commentstyle=\color{red}\itshape, stringstyle=\color{red},

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#+TITLE:     Testing and debugging

#+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

* Outline 

  - What software Testing is? 

  - Learn to test simple functions for their functionality.

  - Learn how to automate tests. 

  -  Need for coding style and some of the standards followed by the Python Community.

  -  Handling Errors and Exceptions.

* gcd function

  - Create gcd.py file with:

#+begin_src python

  def gcd(a, b):

        if a % 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

* Automating tests

#+begin_src python

    if __name=__='__main__':

    for line in open('numbers.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

#+end_src

* Question 1

  For the same inputs as gcd write automated tests for LCM.

* Solution 1

#+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

#+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

* Question 2

   - Give meaningful names to the variables in following

     code

     - c = a / b

* Solution 2

#+begin_src python

  quotient = dividend / divisor

#+end_src

* Code Snippet

#+begin_src python

  while True print 'Hello world'

#+end_src

* Error

#+begin_latex

\begin{lstlisting}

 while True print 'Hello world'

 \end{lstlisting}

  \begin{lstlisting}

  File "<stdin>", line 1, in ?

    while True print 'Hello world'

SyntaxError: invalid syntax

\end{lstlisting}

#+end_latex

* Code Snippet

#+begin_src python

  a = raw_input("Enter a number")

  try:

	num = int(a)

   except:

	print "Wrong input ..."

#+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

 - Create simple tests for a function.

 - Learn to Automate tests using many predefined test cases.

 - Good coding standards.

 - Difference between syntax error and exception.

 - Handling exception using try and except.

 - Using %debug for debugging on ipython.

* Thank you!

#+begin_latex

  \begin{block}{}

  \begin{center}

  This spoken tutorial has been produced by the

  \textcolor{blue}{FOSSEE} team, which is funded by the 

  \end{center}

  \begin{center}

    \textcolor{blue}{National Mission on Education through \\

      Information \& Communication Technology \\ 

      MHRD, Govt. of India}.

  \end{center}  

  \end{block}

#+end_latex