Welcome to the first lesson of our course on Test Driven Development (TDD) in TypeScript using Jest. TDD is an iterative software development process where tests are written before the actual code. This approach enables programmers to focus on the requirements before diving into implementation, ultimately leading to code that is more reliable and maintainable.
In this lesson, we will introduce you to the essential elements of TDD, including the Red-Green-Refactor cycle, which forms the backbone of this methodology. We'll also introduce the tools we'll be using: TypeScript and `Jest. TypeScript is a popular superset of JavaScript that adds static types, helping you catch potential bugs during development. Jest is a widely-used testing framework for JavaScript that seamlessly integrates with TypeScript, providing a comprehensive solution for defining and running tests. Alternatives like Mocha and Chai exist, but Jest's simplicity and power make it an excellent choice for this course. Let's begin by exploring TDD's core components with an example.
In TDD, the journey begins with writing a test that fails. This "Red" stage allows you to clarify your objective before implementation. Let's start by writing a test for a sum function, which will eventually add two numbers.
Create a file named math.test.ts in the test directory:
This test script:
