1 hour Presentation of the basic of TDD in Python 20" Presentation 30" Demo 10" Q&A

1. TDD in Python
PyDayBo
Facoltà di Ingegneria
Università di Bologna
18 marzo 2010
Roberto Bettazzoni
roberto@bettazzoni.it

2. Test Driven Development
Agile practice

3. Prerequisites
●
Code refactoring
●
Incremental design
●
Test First Programming
●
Unit Test

4. Code Refactoring
“In software engineering, ‘refactoring’ source code
means improving it without changing its overall
results.”
Wikipedia: refactoring

5. Incremental Design
“Invest in the design of the system every day.”
Kent Beck, Extreme Programming Explained 2nd Ed. 2004

6. Test First Programming
“Write a failing automated test before changing any
code.”
Kent Beck, Extreme Programming Explained 2 nd Ed. 2004

7. Unit Test
White box test at code level

8. Test-Driven Development
Test First Programming
+ Code Refactoring
+ Incremental design
+ very short iterations (minutes)

9. The T.D.D. process
Add a test
Run tests
see new failure
Refactor
Write some code
Run tests
see all pass

10. DEMO

11. The legacy
expenses.py
Python script used by the employees when they
are abroad to collect the expenses

12. Expenses.py examples
> expenses.py reset
> expenses.py list
> expenses.py put lunch 28.00
> expenses.py put gasoline 50
> expenses.py put lunch 23.50
> expenses.py put hotel
85
> expenses.py get lunch
51.50
> expenses.py get lunch hotel
136.50
> expenses.py get
186.50

13. User Story
As an employee
I want to use my expenese program via web
so I can collect the expenses with a device
that does not support Python

14. Idea

15. Tasks
●
Create a web server
●
Create the HTML page (ask Peter)
●
Read the HTTP parameters
●
Test the legacy
●
●
Refactor the legacy to connect to the HTML
commands
Build the damn thing!

16. Agile Manifesto
We are uncovering better ways of developing
software by doing it and helping others do it.
Through this work we have come to value:
Individuals and interactions over processes and tools
Working software over comprehensive documentation
Customer collaboration over contract negotiation
Responding to change over following a plan
That is, while there is value in the items on
the right, we value the items on the left more.

17. License agreement
●
●
At least part of the material used in this presentation has been
licensed as Creative Common, non-commercial, share-alike
content (http://creativecommons.org/licenses/by-nc-sa/3.0/de/deed.en)
from Roberto Bettazzoni.
As per the license agreement you are entitled to do whatever
you like to the material as far as is not contradicting basic
principle of the license. On top of that Roberto Bettazzoni kindly
asks you to return any change you will make to this material, for
validation and sharing purposes.