Introduction

The purpose of this book is not to evangelize that unit testing will save you time and money in your development process and that it will improve the quality of your product, but rather to:

• Provide the necessary information for you to intelligently balance unit testing with the rest of your development effort and associated costs.
• Provide guidance on how to develop meaningful unit tests.
• Consider which technologies you want to utilize as a unit test engine.
• Consider how unit tests affect the coding style and architecture of your application.

Code Examples

All code examples have been tested in both Visual Studio 2008 Pro with .NET 3.5 and Visual Studio 2012 Pro with .NET 4.5.

Screenshots

Due to changes in the Test Explorer window of Visual Studio 2012, the test result screenshots are from Visual Studio 2008, which has a layout more suitable for conveying both the test result and the test result message. The exceptions to this are screenshots from other unit test applications, such as NUnit.

Expectations of the Reader

The reader is expected to have knowledge of C# and the .NET Framework. Some of the examples require knowledge of lambda expressions and LINQ.

Organization of this Book

The first part of this book discusses the purpose, philosophy, and practice of unit testing:

• Why Unit Test
• What is Unit Testing
• Proving Correctness
• Strategies for Implementing Unit Tests
• Look before You Leap: The Cost of Unit Testing

“How Does Unit Testing Work?" describes how a unit test engine works by creating a simple console-based unit test engine.

“Common Unit Test Tools” is a brief overview of unit testing engines.

Writing unit tests with Visual Studio’s unit test engine and NUnit are then covered in detail in the following chapters:

• “Testing Basics”
• “Unit Testing with Visual Studio”
• “Unit Testing with NUnit”

The book concludes with a discussion of advanced unit testing, dealing with code coverage and techniques for accessing internal fields and methods, followed by a chapter on other uses for unit testing.