There's a popular idiom in software engineering: in order to understand recursion, you must first understand recursion. This lab provides an environment for practicing writing recursive algorithms for a few challenging examples. Starting with a simple case of calculating the factorial of a number, you will be guided through the process of writing tests to define the behavior (Test-Driven Development or TDD) and then determining the base case and recursive step to solve the problem. You will then use what you have learned to solve the more challenging cases of calculating the Fibonacci sequence, and solving the "Tower of Hanoi" puzzle using recursive algorithms. This lab uses the programming language TypeScript, so some familiarity with TypeScript or JavaScript (ECMA Script 2016) will be helpful to complete the lab. There are code samples throughout the documentation that will help you along, and checkpoints included for you to check out working code if necessary.

Legacy code, code that is not under active development or has been passed on to a new engineering team, carries a stigma of being difficult to change and/or maintain. It is often treated as a black box that cannot be altered due to fear of repercussions. This fear does not have to exist, and legacy code can be adopted and improved through refactoring practices. This lab will walk you through the process of adding "characterization tests" to the code that has been provided, and then guide you through several refactoring cycles to make the code easier to understand and maintain. Through this, you will learn and practice effective refactoring techniques.

Putting test-driven development into practice is the best way to learn to apply TDD effectively. This lab allows you to explore TDD by implementing a "To Do" Application Programmer Interface (API) using JavaScript. This application uses a database to persist data, which means that you will need to follow best-practices to test interfaces to third-party systems effectively. During this lab, you will work to implement both the tests that drive the intended behavior of the application and the code that satisfies those tests. This lab is implemented using JavaScript (ES6). Some experience with JavaScript will be helpful to complete the lab, but there are code samples provided in the documentation that can help you if you are unsure.

This lab will guide you through the process of test-driven development (TDD) for code with external dependencies. The lab covers mocking dependencies both by hand and using a mocking framework. The code for this lab will be written using JavaScript (ES6).

In this lab you turn a website into a Progressive Web Application, this way it can run on a edge device without an Internet connection.

This lab will guide you in the process of implementing a stack object through test-driven development (TDD) practices. The tests are written for you; follow the documentation to implement the features of the stack and pass the tests one-by-one. This lab is implemented using JavaScript (ES6). Some experience with JavaScript will be helpful to complete the lab, but there are code samples provided in the documentation that can help you if you are unsure.