BBD Hands-on with Python. Practical Hands-on Workshop about "Behaviour Driven Development", implementing the Game "CodeBreaker" on Python 2.7 as Example

2015-03-28 - 2015-03-29 BDD Hands-on with Python 1

BBD Hands-on with Python

Practical Hands-on Workshop about"Behaviour Driven Development", implementing

the Game "CodeBreaker" on Python 2.7 as Example

PythonCamp Cologne, 2015-03-28 - 2015-03-29

Lecturer: Rolf Hemmerling

Slides: http://www.slideshare.net/hemmerling/License: Creative Commons - Attribution-ShareAlike 4.0 Generic ( http://www.creativecommons.org/licenses/by-sa/4.0/ )

http://www.slideshare.net/hemmerling/

http://www.creativecommons.org/licenses/by-sa/4.0/


Agenda

1. CodeBreaker – The Game

2. Gherkin – The BDD Language

3. GUI Design Process

4. Coding..

5. PEP8 Compliance

6. Setup by distutils, Installation by setup.py, Publication on GitHub, Test & Correction

7. Project Feedback

8. Project Roadmap

9. Resources


1 CodeBreaker – The Game

● Goal: You have to guess a 4-digit secret number

● Howto: You get hints after each guess

● "+" = Right Number at right place● "-" = Right number, but wrong place

● End of Game: If you got the right number

Example:

Secret Number = "1134"

Guess = "5115"

Hint = "+-"


2.1 Gherkin – The BDD Language

Feature: code-breaker starts game

As a code-breaker

I want to start a game

So that I can break the code

@StartGame

Scenario: start game

Given I am not yet playing

When I start a new game

Then I should see "Welcome to Codebreaker!"

And I should see "Enter guess:"


2.2 Gherkin – The BDD Language

Feature: code-breaker submits guess

Scenario Outline: submit guess

Given the secret code is "<code>"

When I guess "<guess>"

Then the mark should be "<mark>"

Scenarios: no matches

| code | guess | mark |

| 1234 | 5555 | |

Scenarios: 1 number correct

| code | guess | mark |

| 1234 | 1555 | + |

| 1234 | 2555 | - |


2.3 BDD Process, Step #1

.feature File BDD source File code

Native language Executable test code


2.4 BDD Process, Step 2..n

.feature BDD Application

Source Code Source Code

Native Executable Executable

language test code application code

executable complies

specification

.feature BDD Application

Source Code Source Code

Native Executable Executable

language test code application code

executable complies

specification


3.1 GUI Design Process - Tools# GUI Designer The generated code

Name Platform GUI Framwork

Screen Layout

Class Runtime License Ok?

1 page Tcl/Tk Tkinter Grid Yes Yes

2 ptkgb Python Tkinter Grid Yes Python megawidgets (pmw)

MIT Yes

3 ptkgen Python Tkinter Grid No tkgen GPL 2.1 Yes

4 pygubu Python TkInter Grid Yes pygubu GPL 3 Yes

5 QT Creator Python QT, PyQT Grid Yes PyQT, QT GPL 2 or 3 Yes

6 rapyd Python Tkinter Grid Yes rpErrorHandler.py Public Domain?

Not yet

6 SpecTCL Python Tkinter Grid Yes Yes

7 tk_happy Python Tkinter Place Yes Yes

9 Visual Python Tkinter IDE 1v1.6

.NET Tkinter Place No No


● If the code by GUI designers needs a runtime, what is the runtime's license ( GPL, LGPL, MIT, public domain,..)?

● Efficent naming - When selecting names for GUI designer objects, think of Python naming conventions!

– Class => CamelCode– Class method / function => Lowercase & underscore– Variable

● Global variable => Capitals only● Local variable => Lowercase & underscore

3.2 GUI Design Process - Practice


1. Domain expert of the customer and software developer

● Creation of BDD documents

2. Software developer

➢ Auto-generation of a basic script

– PowerShell.exe -ExecutionPolicy Unrestricted➢ behave my.feature 2>&1 >my.py

➢ Make the script runable ( avoid $FF in the file )

➢ Implement a step

➢ Implement steps with variables

➢ Implement steps with regular expressions

➢ Test-driven Implementation of the application, using PyUnit

4 Coding...


3 Domain expert of the customer and software developer

● Integration test of the application

● Presentation and roll-out of the application

● Project feedback

4 Coding...


● Most GUI designers create code which

● Doesn´t complie with PEP8...

● Isn't passed by codecheckers ( PyLint.. ) without much warnings...

● Often doesn´t meet the Python naming conventions,

– By the tool

– Or by user's wrong choice when using the tool!● Love it or leave it!

● If you must complete the generated code files, manually

– If you know that you will or can never use the GUI designer again, then you might once modify the code to make it PEP8 / PyLint compliant

● Else ( PyQT => Class derivation ) .. accept the code as it is

● Yet another project for the GUI designer: Modify the code generator... :-)

5 PEP8 Compliance


<dev_root>codebreaker.py

<dev_root>/Scripts/codebreaker-script.py

<dev_root>/project/d_implementation/steps => <inst_root><codebreaker_package>

Setup.py

from distutils.core import setup

setup(name='codebreaker',

version='1.0',

data_files=[('Lib/site-packages/codebreaker_package', ['AUTHORS', 'COPYING', 'README.txt']),

('Scripts', ['Scripts/codebreaker.bat', 'Scripts/codebreaker.sh']) ],

scripts=['Scripts/codebreaker-script.py'],

py_modules=['Scripts/codebreaker-script', 'codebreaker'],

package_dir={'codebreaker_package': 'project/d_implementation/steps'},

packages=['codebreaker_package'])

6.1 Setup by distutils


cd /<dev_root>

setup sdist

REM "<dev_root>/dist/codebreaker-1.0.zip" is created

cd dist

unzip codebreaker-1.0.zip

setup install

REM The directory "<dev_root>/build" is created

cd /<dev_root>

setup.py bdist_wininst

REM "<dev_root>/dist/codebreaker-1.0.win32.exe" is created

6.2.1 Installation by setup.py


setup install

c:\Python27\Lib\

c:\Python27\Lib\side-packages

c:\Python27\Scripts



virtualenv c:\Users\Public\python

setup.py install –prefix="c:\Users\Public\python"

c:\Users\Public\python\Lib\site-packages

c:\Users\Public\python\Lib\site-packages\codebreaker_package

c:\Users\Public\python\Lib\site-packages\Scripts

c:\Users\Public\python\Script

set_pythonhome.bat

set path=%path%;c:\users\public\python\Scripts

set pythonhome=c:\users\public\python

set_pythonpath.bat

set path=%path%;c:\users\public\python\Scripts

set pythonpath=c:\users\public\python\Scripts;c:\users\public\python\Lib;c:\users\public\python\Lib\site-packages



REM Test

cd \users\public

codebreaker

codebreaker -i page

REM Correction

cd c:\Python27\Scripts

ren pygubu.pyw pygubu-script.py

copy con pygubu.bat

Pygubu-script.py

^z

6.3 Test & Correction


C:\Users>codebreaker.bat

C:\Users>codebreaker-script.py

Running Python sys.version_info(major=2, minor=7, micro=6, releaselevel='final',

serial=0) on 'win32'

Traceback (most recent call last):

File "C:\Python27\Scripts\codebreaker-script.py", line 31, in <module>

import codebreaker

File "C:\Python27\lib\site-packages\codebreaker.py", line 31, in <module>

from codebreaker_package.cb import main as cb_main

File "C:\Python27\lib\site-packages\codebreaker_package\cb.py", line 36, in <m

odule>

from pygubu_codebreaker import main as pygubu_main

File "C:\Python27\lib\site-packages\codebreaker_package\pygubu_codebreaker.py"

, line 33, in <module>

import pygubu

File "C:\Python27\Scripts\pygubu.pyw", line 43, in <module>

print("Pygubu: v. %s" % (pygubu.__version__,))

AttributeError: 'module' object has no attribute '__version__'

6.4 Pygubu Module - Problem

File "C:\Python27\Scripts\pygubu.pyw", line 43, in <module>


.gitignore

.pypirc

*.zip

*.exe

*.rpm

build

bin

dist

6.5 Publication on GitHub


7 Project Feedback

● If BDD is intended to describe business logic, what to do with UI messages?

● BDD does not help to describe business algorithms ( in opposite to UML, BPMN )

● Tricky "Scenarios: matches with duplicates"

● TDD & Unittests => helpful

● I felt helpless with BDD

● Behave produces much output garbage

● Integration with IDEs, with information filtering would be helpful

● Setup implementation

● revealed errorous naming of script file of a dependant module ( Pygubu )

● Distutils doesnt' handle requirements ( requires=["required_module"] ) as promised


8 Roadmap

● Webserver-based versions ( Bottle, CherryPy, Django, Genshi, Gunicorn, Plone/Zope, Pocco "Flask", Pylons Project "Pyramid", Python Paste, Tornado )

● Further GUI-based versions ( Kivy, wxPython, PyGTK.. ),

● Online-service based versions ( Heroku, PythonAnywhere,..)

● Module for the ERP systems Tryton / OpenERP

● Implementation for other installers ( i.e. Setuptools / Easy Install )


9 Resources

● Book

● David Chelimsky, Dave Astels, Bryan Helmkamp, Dan North, Zach Dennis, Aslak Hellesoy: "The RSpec Book: Behaviour Driven Development with RSpec, Cucumber, and Friends", ISBN 1934356379

● Rolf Hemmerling's webpage, also about BDD http://www.hemmerling.com/doku.php/en/specbyex.html

● Rolf Hemmerling's webpage, also about GUI designers http://www.hemmerling.com/doku.php/en/python.html

● Rolf Hemmerling's Slides http://www.slideshare.net/hemmerling/

http://www.hemmerling.com/doku.php/en/specbyex.html

http://www.hemmerling.com/doku.php/en/python.html

http://www.slideshare.net/hemmerling/