Book Image

RSpec Essentials

By : Mani Tadayon
Book Image

RSpec Essentials

By: Mani Tadayon

Overview of this book

This book will teach you how to use RSpec to write high-value tests for real-world code. We start with the key concepts of the unit and testability, followed by hands-on exploration of key features. From the beginning, we learn how to integrate tests into the overall development process to help create high-quality code, avoiding the dangers of testing for its own sake. We build up sample applications and their corresponding tests step by step, from simple beginnings to more sophisticated versions that include databases and external web services. We devote three chapters to web applications with rich JavaScript user interfaces, building one from the ground up using behavior-driven development (BDD) and test-driven development (TDD). The code examples are detailed enough to be realistic while simple enough to be easily understood. Testing concepts, development methodologies, and engineering tradeoffs are discussed in detail as they arise. This approach is designed to foster the reader’s ability to make well-informed decisions on their own.
Table of Contents (17 chapters)
RSpec Essentials
About the Author
About the Reviewers

Test-driven development

It seems to make sense to write your code first and then to test it, as we did in our AddressValidator example above. Many people follow this approach. However, many others follow a process called TDD, where the tests are written first. Why do this? Let's take a brief aside before answering the question.

If you look at RSpec's official documentation, you will find that instead of the word test, the word example is used to describe the individual assertions to be found within the it block. Although it may appear less natural than test, in some ways example is more accurate. Automated tests rarely provide conclusive proof that a software system, or even just one of its functions, works. Most often, they contain a few test cases, which are nothing but examples of the code in action. Moreover, one of the main benefits of an automated assertion is to document the way the code behaves. Whereas test suggests a proof of correctness, example just suggests an instance of the code in action.

Coming back to the question of why someone would write their test before their code, we can apply the concept of the example. A methodical software engineer could benefit from documenting the code about to be written with some examples. Rather than adding these as comments in the code, the documentation can be written in the form of automated tests, or assertions. This way, as the code is being written, the tests can be run to give some feedback about how close, or how far, the code is to performing as initially expected.

If we refer to RSpec's home page, there is a link provided (, where we can read the following description:

RSpec is a Behaviour-Driven Development tool for Ruby programmers. BDD is an approach to software development that combines Test-Driven Development, Domain Driven Design, and Acceptance Test-Driven Planning. RSpec helps you do the TDD part of that equation, focusing on the documentation and design aspects of TDD.

We see that TDD is mentioned, but the first sentence identifies RSpec with BDD. Although a definition is given, it refers to three other methodologies, leaving us perhaps with only a vague impression of some fancy approach to software development. So what is BDD really?