Python-3.4.3/C4/Testing-and-Debugging/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to the spoken tutorial on Testing and debugging. |
| 00:06 | In this tutorial, you will, Understand what is software testing |
| 00:11 | Test simple functions for their functionality |
| 00:15 | Automate tests |
| 00:17 | Understand the need for coding style and Learn some of the standards followed by the Python Community |
| 00:25 | To record this tutorial, I am using
Ubuntu Linux 16.04 operating system |
| 00:32 | Python 3.4.3 |
| 00:35 | IPython 5.1.0 and Gedit text editor |
| 00:42 | To practise this tutorial, you should know how to use functions. |
| 00:48 | If not, see the relevant Python tutorials on this website. |
| 00:53 | First we will learn about software testing. |
| 00:57 | Software testing is the process to evaluate the functionality of a software or a program. |
| 01:04 | It helps to find whether the program met the specified requirements or not. |
| 01:10 | It ensures a defect free program so that we will get a quality program. |
| 01:16 | All the codes used in this tutorial are available in the Code Files link of this tutorial. |
| 01:23 | You should download in the current working directory and use them. |
| 01:28 | Open any text editor and type the following code. |
| 01:33 | This is a simple function to calculate gcd of two numbers. |
| 01:38 | We need a set of inputs for the variable a and b. |
| 01:43 | Save the file as find underscore gcd.py in the current working directory. |
| 01:50 | Next we will open the file test underscore gcd.py. |
| 01:56 | Let our test case be 48 and 64 as a and b. |
| 02:02 | For this test case we know that the GCD is 16. So that is the expected output. |
| 02:11 | Let us now run the script and test our code. |
| 02:15 | Open the terminal and type python3 test underscore gcd.py |
| 02:24 | We get the output as Test Passed which means our code is correct. |
| 02:30 | But there can be a number of cases where the gcd function might break. |
| 02:36 | So, to check where our code is breaking we should run many tests. |
| 02:42 | This is where the concept of automating tests comes in. |
| 02:46 | Let us first try and automate tests on the gcd function. |
| 02:51 | Open the file textcases.txt where the various testing parameters are given. |
| 02:58 | The structure of the file will have two input parameters. |
| 03:03 | The third parameter is the correct output result. We have separated the elements by a space. |
| 03:11 | Next let us open the file automate underscore test underscore gcd.py |
| 03:18 | First we need import gcd function from find underscore gcd in order to use it for testing. |
| 03:26 | Next the testcases.txt file is read line by line. |
| 03:32 | The first two input parameters are assigned to the variables x and y. |
| 03:38 | The third parameter which is the correct output value is assigned to the variable result. |
| 03:44 | We check whether the value returned by the gcd function is equal to the value in the variable result. |
| 03:52 | Finally it prints the message accordingly. |
| 03:56 | In the terminal, type python3 automate underscore test underscore gcd.py |
| 04:05 | As you can see, all the three test cases in testcases.txt are passed. |
| 04:12 | The value calculated by the gcd function is equal to the output value provided in the testcases.txt. |
| 04:20 | Pause the video. Try this exercise and then resume the video. |
| 04:26 | For the same inputs as gcd write automated tests for LCM. |
| 04:33 | Use the data from the file lcmtestcases.txt |
| 04:38 | Switch to the terminal for the solution. |
| 04:42 | Let us see the code to calculate lcd of two numbers.
The file name is find underscore lcm.py |
| 04:52 | This is the data file for the lcm test cases. |
| 04:57 | This file name is lcmtestcases.txt |
| 05:02 | Note that both these files should be in the current working directory. |
| 05:07 | Let us now run the script and test our code. |
| 05:11 | Type python3 find underscore lcm.py |
| 05:17 | Here, the third test case failed. Because the corresponding input in lcmtestcases.txt is incorrect. |
| 05:26 | This is to check the behavior of the program on incorrect conditions. |
| 05:32 | A good program should be readable. So others can extend and improve it. |
| 05:39 | Code is read more often than it is written. |
| 05:43 | We choose a name so that it becomes easier to understand its usage. |
| 05:49 | As we can see in the example, it is very easy to understand what the code is doing. |
| 05:55 | Proper naming helps so much in understanding the code. |
| 06:00 | Also one should keep in mind the following things while writing a code in Python. |
| 06:06 | Four Space Indentation |
| 06:09 | 79 characters limit on a line |
| 06:13 | Functions and methods should be separated with two blank lines. |
| 06:18 | Use Docstring to document a specific segment of code. |
| 06:23 | Use whitespace around operators and after punctuations. |
| 06:28 | This brings us to the end of this tutorial. Let us summarize. |
| 06:34 | In this tutorial, we have learnt to,
Create simple tests for a function |
| 06:40 | Automate tests using many predefined test cases and Use python coding standards. |
| 06:49 | Here is a self assessment question for you to solve |
| 06:53 | What is the proper indentation for python code according to the style guidelines? |
| 06:59 | And the answer, Four Space Indentation is required for writing a python code according to the style guidelines. |
| 07:08 | Please post your timed queries in this forum. |
| 07:12 | Please post your general queries on Python in this forum.
FOSSEE team coordinates the TBC project. |
| 07:22 | Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India. For more details, visit this website. |
| 07:33 | This is Priya from IIT Bombay signing off. Thanks for watching. |
