Book Image

Django 1.1 Testing and Debugging

Book Image

Django 1.1 Testing and Debugging

Overview of this book

Bugs are a time consuming burden during software development. Django's built-in test framework and debugging support help lessen this burden. This book will teach you quick and efficient techniques for using Django and Python tools to eradicate bugs and ensure your Django application works correctly. This book will walk you step by step through development of a complete sample Django application. You will learn how best to test and debug models, views, URL configuration, templates, and template tags. This book will help you integrate with and make use of the rich external environment of test and debugging tools for Python and Django applications. The book starts with a basic overview of testing. It will highlight areas to look out for while testing. You will learn about different kinds of tests available, and the pros and cons of each, and also details of test extensions provided by Django that simplify the task of testing Django applications. You will see an illustration of how external tools that provide even more sophisticated testing features can be integrated into Django's framework. On the debugging front, the book illustrates how to interpret the extensive debugging information provided by Django's debug error pages, and how to utilize logging and other external tools to learn what code is doing.
Table of Contents (17 chapters)
Django 1.1 Testing and Debugging
Credits
About the Author
About the Reviewer
Preface
Index

Getting started with the debugger


A debugger is a powerful development tool that allows us to see what code is doing as it runs. When a program is run under the control of a debugger, the user is able to pause execution, examine and change the value of variables, flexibly continue execution to the next line or other explicitly set "breakpoints", and more. Python has a built-in debugger named pdb which provides a user interface that is essentially an augmented Python shell. In addition to normal shell commands, pdb supports various debugger-specific commands, many of which we will experiment with in this chapter as we debug the survey results display code.

How, then, do we use pdb to help figure out what is going on here? We'd like to enter the debugger and step through the code to see what is happening. The first task, breaking into the debugger, can be accomplished by adding import pdb; pdb.set_trace() wherever we'd like the debugger to get control. The set_trace() call sets an explicit...