Book Image

Practical Test-Driven Development using C# 7

By : John Callaway, Clayton Hunt
Book Image

Practical Test-Driven Development using C# 7

By: John Callaway, Clayton Hunt

Overview of this book

Test-Driven Development (TDD) is a methodology that helps you to write as little as code as possible to satisfy software requirements, and ensures that what you've written does what it's supposed to do. If you're looking for a practical resource on Test-Driven Development this is the book for you. You've found a practical end-to-end guide that will help you implement Test-Driven Techniques for your software development projects. You will learn from industry standard patterns and practices, and shift from a conventional approach to a modern and efficient software testing approach in C# and JavaScript. This book starts with the basics of TDD and the components of a simple unit test. Then we look at setting up the testing framework so that you can easily run your tests in your development environment. You will then see the importance of defining and testing boundaries, abstracting away third-party code (including the .NET Framework), and working with different types of test double such as spies, mocks, and fakes. Moving on, you will learn how to think like a TDD developer when it comes to application development. Next, you'll focus on writing tests for new/changing requirements and covering newly discovered bugs, along with how to test JavaScript applications and perform integration testing. You’ll also learn how to identify code that is inherently un-testable, and identify some of the major problems with legacy applications that weren’t written with testability in mind. By the end of the book, you’ll have all the TDD skills you'll need and you’ll be able to re-enter the world as a TDD expert!
Table of Contents (21 chapters)
Title Page
Packt Upsell
Foreword
Contributors
Preface
4
What to Know Before Getting Started
Index

Typical issues resulting from legacy code


There is a reason we fear working on legacy code. But, what is it that we fear when working on legacy code? It's not the code itself; the code cannot harm us. Instead, what we fear is hearing that we have introduced a bug. The most dreaded word that a developer can hear. A bug means that we have failed and that we will have to work on the legacy code again.

Exploring the types of issues we might run into while working on legacy code, we find several. Firstly, because we don't know the code, a change to one part might cause unintended side effects in a different part of the application. Another issue is the code could be over-optimized or written by someone who was trying to be clever when they wrote it. Lastly, tight coupling can make updating the code difficult.

Unintended side effects

With all the changes that push an application towards the legacy realm, often the methods or functions in the application will be used in unexpected places, far away...