The Art of Unit Testing, Third Edition</i> updates an international bestseller to reflect modern development tools and practices. This expanded edition teaches you to write unit tests for async and observable code, as well as methods of faking functions, modules and refactorings. You'll explore test patterns and organization, working with legacy code, and even "untestable" code. The many tool-agnostic examples are presented in JavaScript, and are carefully designed so that they apply to code written in any language.