Book Image

The Clojure Workshop

By : Joseph Fahey, Thomas Haratyk, Scott McCaughie, Yehonathan Sharvit, Konrad Szydlo
Book Image

The Clojure Workshop

By: Joseph Fahey, Thomas Haratyk, Scott McCaughie, Yehonathan Sharvit, Konrad Szydlo

Overview of this book

The Clojure Workshop is a step-by-step guide to Clojure and ClojureScript, designed to quickly get you up and running as a confident, knowledgeable developer. Because of the functional nature of the language, Clojure programming is quite different to what many developers will have experienced. As hosted languages, Clojure and ClojureScript can also be daunting for newcomers because of complexities in the tooling and the challenge of interacting with the host platforms. To help you overcome these barriers, this book adopts a practical approach. Every chapter is centered around building something. As you progress through the book, you will progressively develop the 'muscle memory' that will make you a productive Clojure programmer, and help you see the world through the concepts of functional programming. You will also gain familiarity with common idioms and patterns, as well as exposure to some of the most widely used libraries. Unlike many Clojure books, this Workshop will include significant coverage of both Clojure and ClojureScript. This makes it useful no matter your goal or preferred platform, and provides a fresh perspective on the hosted nature of the language. By the end of this book, you'll have the knowledge, skills and confidence to creatively tackle your own ambitious projects with Clojure and ClojureScript.
Table of Contents (17 chapters)
Free Chapter
2
2. Data Types and Immutability

Using the Expectations Testing Library

The main philosophy in the Expectations library revolves around an expectation. The expectation object is built with the idea that unit tests should contain one assertion per test. A result of this design choice is that expectations have very minimal syntax, and reduce the amount of code needed to perform tests.

Minimal syntax helps to maintain the code as it is easier to read and reason about code that is short and focused on testing one feature. Another benefit relates to testing failing code. When a test fails, it is easy to check which test failed and why because the test is focused on one feature and not multiple features.

The Expectations library allows us to test things like the following:

  • Errors thrown by the code: We can test whether a part of our code throws an error. Imagine a function that calculates a discount. This function takes numbers as input and multiplies them. If we pass a string such as "text" and...