When building software, we need to make sure everything works as expected. That’s where unit tests and integration tests come in. These two types of tests help us check different parts of the code but serve very different purposes.
What Are Unit Tests?
Unit tests focus on testing small pieces of code—like individual functions or methods—by themselves. Think of them as zooming in to test one tiny part of your app. The Purpose is to make sure a specific piece of code works exactly how it’s supposed to.
- Example: Testing if a function that calculates the total price of a shopping cart adds up correctly.
- Speed: Super quick because it only tests small bits of the app.
- Dependencies: Often doesn’t rely on external systems like databases or APIs. If it needs them, we “mock” them (fake them).
What Are Integration Tests?
Integration tests check how different parts of your app work together. Instead of testing one function, they test workflows or connections between parts of your system.
- Purpose: Make sure everything works smoothly when multiple parts of the app interact, such as connecting to a database or calling an API.
- Example: Testing if your app can fetch a user’s data from a database and display it correctly.
- Speed: Slower because it deals with real systems like databases, APIs, or file storage.
- Dependencies: Usually connects to real systems, though some might still be mocked
How Are They Different?
| Unit Tests | Integration Tests |
|---|---|
| Test small pieces of code | Test how different parts work together |
| Use fake (mocked) systems | Often use real systems |
| Fast to run | Slower to run |
| Focus on one function or method | Focus on workflows or connections |
When Do You Use Them?
- Use unit tests early in development to make sure small parts of your code are working.
- Use integration tests to catch bugs that happen when different parts of your app interact, like when a database query doesn’t return the right data.
By understanding unit and integration tests, you’ll be better prepared to write solid code and troubleshoot bugs before they become big problems!
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