Software Testing

Welcome to Module 06! Now that we have built a full-stack application with a frontend, backend, database, and authentication, it is crucial to ensure that it works as expected and continues to work as we add new features. This is where Software Testing comes in.

What You Will Learn

In this module, we will cover:

• Software Testing Fundamentals: Why we test and the different types of tests.
• The Testing Pyramid: Understanding Unit, Integration, and End-to-End (E2E) tests.
• Backend Testing: Testing Hono API handlers and middleware using Bun Test.
• Frontend Testing: Testing React components using React Testing Library (RTL).

Why Test?

Testing might seem like extra work, but it provides immense value:

1. Confidence: You can deploy changes knowing you haven’t broken existing functionality.
2. Documentation: Tests serve as living documentation of how your code is supposed to work.
3. Regression Prevention: Tests catch bugs that reappear after being fixed.
4. Refactoring Safety: You can improve your code structure without changing its behavior, verified by tests.

The Testing Pyramid

The “Testing Pyramid” is a concept that suggests how many of each type of test you should have:

• Unit Tests (Base): Fast, isolated, and numerous. They test individual functions or components.
• Integration Tests (Middle): Slower, test how parts work together (e.g., API + Database).
• End-to-End (E2E) Tests (Top): Slowest, test the entire flow from the user’s perspective (e.g., clicking through the app).

In this module, we will focus primarily on Unit and Component testing.

Tooling: Bun Test

Since we are using Bun as our runtime, we have access to a built-in test runner that is incredibly fast and compatible with Jest (a popular testing framework).

• Fast: No need to wait seconds for tests to start.
• Compatible: Uses familiar describe, test, expect syntax.
• Built-in: No extra packages to install for the runner itself.

Let’s dive in!