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

Tracking internal code state


Sometimes even all of the information available from a tool like the Django Debug Toolbar is not enough to figure out what is going wrong to produce incorrect results during processing of a request. The problem probably lies somewhere in the application code, but from visual inspection we just cannot figure out what is wrong. To solve the problem we need to get more information about the internal state of the application code. Perhaps we need to see what the flow of control is through the functions in the application, or see what values are calculated for some intermediate results that ultimately cause the code to go down a wrong path.

How do we get this kind of information? One way is to run the code under a debugger, and actually step through it line by line to see what it is doing. This approach will be covered in detail in the next chapter. It is very powerful, but can be time-consuming and is not practical in all situations. For example, it is difficult to...