Saturday, October 24, 2009

Chapter 2. Getting Started: Tutorial











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Chapter 2. Getting Started: Tutorial







Software concepts are best explained by example. In this tutorial,

you will set up a simple unit test framework and use it to help build

a basic application. Following the primary rule of TDD, every change

to the code is preceded by a unit test.





Why build our own test framework, instead of starting with one of the

xUnits? The xUnit test frameworks are powerful tools.

They not only support writing unit tests, running them, and reporting

the results, but also include test classes, helper code, test

runners, and utilities. Such features minimize the amount of code

required to write a unit test and maximize your ability to test

complex code. They include much more than the minimum needed to build

unit tests.





The core functionality of running tests and reporting the results is

fundamentally simple. Developers working in cross-platform

environments, using older compilers or uncommon languages or needing

closer control over how unit tests and their results are handled may

not be able to use the xUnits or want to invest the time to set them

up. The proliferation of very basic unit test frameworks available

online demonstrates the popular belief that "simpler

is better" when it comes to unit test frameworks.

Most importantly, creating your own framework clearly demonstrates

how unit tests work and how straightforward the unit test framework

concept really is.





The example code is given in Java. Appendix A contains the C++

version. The code can be found on the CD accompanying this book in

the directory /examples/chapter2. Consider

entering the code in this chapter by hand as if you were coding it

from scratch. It's an illuminating exercise that

will help you to understand how quick and easy it is to set up and

start using a unit test framework.





This tutorial assumes that you have a

Java runtime environment and

compiler

installed. Sun's

javac compiler is recommended, as is the

GNU gcj Java

compiler. Versions of both compilers are readily available for most

platforms.





The step-by-step procedures given here assume that you are compiling

and running the code from the command line. If you are using a

graphical Integrated Development Environment

(IDE), the details of how you build and run the example code will

differ.



















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