# Typescript ESM icin Jest calistirmak

> Bunu kurmak ve dokumante etmek 2:30 saatimi aldı, gerçekten inanılmaz sıkıcı 😅

> 💡 Sifirdan npm projesi olusturacaksaniz [npm-package-template](https://github.com/yemreak/npm-package-template) template’ime bir bakin

## `package.json` yapilandirmasi

* `jest` yapilandirma bilgilerini `package.json` icine ekleyin
* `jest.config.js` kullanmaniza gerek yoktur
* `moduleNameMapper` ayari ile `ESM`den gelen zorunlu `import.js` kuralini duzenliyoruz
* `^.+\\.ts$` ile de `esm` kullanimini typecript kodlari icin aktif ediyoruz

```javascript
// {...
"jest": {
	"preset": "ts-jest",
	"testEnvironment": "node",
	"silent": true,
	"extensionsToTreatAsEsm": [
		".ts"
	],
	"moduleNameMapper": {
		"^(\\.{1,2}/.*)\\.js$": "$1"
	},
	"transform": {
		"^.+\\.ts$": [
			"ts-jest",
			{
				"useESM": true
			}
		]
	}
},
// ...}
```

## VSCode icin `launch.json` yapilandirmasi

```javascript
{
	"name": "Jest",
	"type": "node",
	"request": "launch",
	"runtimeArgs": [
		"--experimental-vm-modules", // <<< onemli
		"${workspaceRoot}/node_modules/.bin/jest",
		"${input:exchange}",
		"-t",
		"${input:testName}",
		"--runInBand"
	],
	"cwd": "${workspaceRoot}",
	"stopOnEntry": false,
	"console": "integratedTerminal",
	"internalConsoleOptions": "neverOpen",
	"sourceMaps": true,
	"windows": {
		"program": "${workspaceFolder}/node_modules/jest/bin/jest"
	},
	"skipFiles": ["<node_internals>/**", "**/node_modules/**"]
},
```

## Hata Notlari

### SyntaxError: Cannot use import statement outside a module

* Jest kullanimi icin `node` ile `experimental-vm-modules` argumanini kullanmaliyiz aksi halde hatasi aliriz

## Eklenti Tavsiyesi

{% embed url="<https://marketplace.visualstudio.com/items?itemName=vespa-dev-works.jestRunIt>" %}

## References

{% embed url="<https://stackoverflow.com/a/69117363/9770490>" %}

{% embed url="<https://jestjs.io/docs/ecmascript-modules>" %}

{% embed url="<https://gist.github.com/danpetitt/37f5c966886f54e457ece4b08d66e404?permalink_comment_id=4710758#gistcomment-4710758>" %}