export const metadata = {
  title: `${pageNumber} Debugging and Testing Tools`,
}

# {metadata.title}

In this chapter, you’ll learn about debugging and testing tools you can use.

<Note title="Tip">

Since the Medusa server is a Node.js server, you can use any Node.js testing tool you prefer, even if it’s not listed here.

</Note>

## Jest

[Jest](https://jestjs.io/) is a JavaScript testing framework. Your Medusa project is already configured with Jest; you can use it out-of-the-box.

For example, consider the following service created at `src/modules/hello/service.ts`:

```ts title="src/modules/hello/service.ts"
import { TransactionBaseService } from "@medusajs/medusa"

class HelloWorldService extends TransactionBaseService {
  constructor(container) {
    super(arguments[0])
  }
  getMessage(): string {
    return "Hello, world!"
  }
}

export default HelloWorldService

```

You can write a test for it in the file `src/modules/hello/__tests__/hello-world.ts`: 

```ts title="src/modules/hello/__tests__/hello-world.ts"
import HelloWorldService from "../hello-world"

describe("HelloWorldService", () => {
  const helloWorldService = new HelloWorldService()

  it("should return hello world message", () => {
    expect(helloWorldService.getMessage()).toBe("Hello, world!")
  })
})
```

Then, run the following command in the root of your Medusa project to run the test:

```bash npm2yarn
npm run test
```

This command looks for TypeScript and JavaScript files under any directory named `__tests__` and runs them.

---

## IDE Debugging Tools

Your IDE may provide a debugging tool for Node.js. In that case, you can use that tool to debug your Medusa customizations.

For example, if you’re using VSCode, refer to [this guide](https://code.visualstudio.com/docs/nodejs/nodejs-debugging) to learn how to configure and use the debugger.

---

## Node.js Debugger

You can also use Node.js’s Debugger API to debug your Medusa customizations.

Refer to [Node.js’s documentation](https://nodejs.org/docs/latest-v18.x/api/debugger.html) for more details.