Geoffrey's Bangalore

From left to right : Me, Jon, Rajeshwar, Ambar and Rob

No Kidding

Australia batting first - 434 for 4 in 50 overs

South Africa - 438 for 8 in 49.5 overs

South Africa Win by 1 wicket with 1 ball to spare !

Test Driven Development

Test Driven Development is a technique for writing the test cases first and then doing incremental coding for each case. This has to be coupled with regression testing after each module for a test case is written. An automated testing environment is a desired requirement for this paradigm.

Inadvertently , we might have done this in past for one or more of our projects. I have done something similar in one of my projects without following the regression testing rule exhaustively.

The way it works - several iterations of the following steps:

• Write a test case for a small feature: use the requirement and the use cases to write test cases.
• Make sure that the test case fails (you haven't written the code for this feature) : There might be a "bug" in your program which gives you this "feature". This requirement basically means "start with a clean slate".
• Write the code necessary to pass the current test case.
• Refractor code - making sure that the code for the new feature fits in the design or the other parts of the code are adjusted to make it the simplest design.
• Regressing testing - run all the test cases written so far

Advantages

• Due to regression testing requirement , the modules are written in a modular way which can be tested individually and hence aids object oriented design.
• Takes out a huge amount of time from a manual regression testing process
• Coding is always done an incremental fashion which makes a loosely coupled system
• Testing for each feature is NOT done as an afterthought
• The initial test case document provides a good document for system capabilities

Limitations and challenges :

• A sound automated testing environment is required to ensure regression testing - hence additional effort required initially. (JUnit is an example of automated testing infrastructure for java and boost test for c++).
• Distributed objects in an environment - can write "mock" objects to support this
• A test driven environment is as good as the test cases, since they are the key design driver.

References :
http://www.objectmentor.com/writeUps/TestDrivenDevelopment
http://en.wikipedia.org/wiki/Test_driven_development