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

Test negative cases first


What does it mean to test negative cases first? In many computer games, especially role-playing games, it is common for the game designers to make it very difficult to win the game if you simply go straight to the boss. Instead, you must make side quests, make wrong turns, and get lost in the story before you can fight the boss. Testing is no different. Before the problem can be solved, we must first handle bad input, prevent exceptions, and resolve conflicts in the business requirements.

In the Todo application, we mistakenly flew through and added an item to the Todo list without verifying that the item was valid. Now, the sprint is over and our user interface developers are mad at us because they do not know what to do with a Todo item that has no details at all. What we should have done is handle the cases where we receive bad data first. Let's rewind and temporarily skip the test we just made. 

[Fact(Skip="Forgot to test negative cases first")]
public void ItAddsATodoItemToTheTodoList...