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# TypeScript kullanarak Bun:test ile Hata Fırlatılmasını Beklemek - ts(2348)

bunjs, typescript, programming, except, async, throw, test

## Basit Örnek

* `() =>` kullanımında dikkatli olun

```javascript
// someFunction.ts
export function someFunction(shouldThrow: boolean): void {
	if (shouldThrow) {
		throw new Error("Ben bir hata'yım!")
	}
}

// someFunction.test.ts
import { someFunction } from "./someFunction"

test("bir hata fırlatmalı", () => {
	expect(() => someFunction(true)).toThrow("Ben bir hata'yım!")
})

test("bir hata fırlatmamalı", () => {
	expect(() => someFunction(false)).not.toThrow()
})

```

## Async Örnek

* `Promise` için `rejects` kullanın

```typescript
it("NotFoundError döndürmeli", () => {
	expect(getUserData("olmayanUserId"))
		.rejects.toBeInstanceOf(NotFoundError)
})

```

## Özel Hata Türleri ile İleri Kullanım

* Uyarıyı önlemek için `CustomError` yerine `new CustomError()` kullanın
* `() =>` kullanımında dikkatli olun

```javascript
// CustomError.ts
export class CustomError extends Error {
	constructor(message: string) {
		super(message)
		Object.setPrototypeOf(this, CustomError.prototype)
	}
}

// someFunction.ts
import { CustomError } from "./CustomError"

export function someFunction(shouldThrow: boolean): void {
	if (shouldThrow) {
		throw new CustomError("Ben özel bir hatayım!")
	}
}

// someFunction.test.ts
import { someFunction } from "./someFunction"
import { CustomError } from "./CustomError"

test("özel bir hata fırlatmalı", () => {
	expect(() => someFunction(true)).toThrow(new CustomError())
	// Uyarıyı önlemek için `new CustomError()` yerine `CustomError` kullanın
	// `() =>` kullanımında dikkatli olun
})

```

## **Value of type "typeof X' is not callable. Did you mean to include 'new'? ts(2348)**

* Gösterilen hatayı önlemek için `new AlreadyAdjusted()` kullanın
* Bu hata calisma sirasinda sorun teskil etmez

```javascript
export class AlreadyAdjusted extends Error {
	constructor() {
		super("Zaten ayarlandı")
	}
}

```

![jRe9NPT.png](https://i.imgur.com/jRe9NPT.png)

![6tNPvSi.png](https://i.imgur.com/6tNPvSi.png)


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