在测试用例中无法工作的流明假图像上传请求 - > hasFile（）返回false

Question

I'm uploading a file in lumen and trying to test it so i follow this example from their documentation

Storage::fake('avatars');

$file = UploadedFile::fake()->image('avatar.jpg');

$response = $this->json('POST', '/avatar', [
    'avatar' => $file,
]);

Now when I do this in lumen the file is empty when I try to pull it from the request:

$request->hasFile('avatar') // Returns false

I also tried:

$response = $this->post( '/avatar', [
    'avatar' => $file,
]);

This fills an image but in $request->input('avatar') not in $request->file('avatar')

When I perform a POST request via Postman it does actually works: Under body I select form-data and choose key type=File and then select a file. postman request

How can I test uploading images in Lumen?