Test fetch with form data

[costiiordan]

When I execute tests on pages that use fetch to send form data to the server, the form data is not sent.
I created a simple example to showcase the issue:

Controller:

class TestController
{
    public function view(): View
    {
        return view('test');
    }
    
    public function handle(Request $request): JsonResponse
    {
        return response()->json(['message' => $request->get('test_input', 'No input provided')]);
    }
}

View:

<html>
<head>
    <title>Test page</title>
</head>
<body>
<button id="test-btn">Test</button>
<div id="response"></div>
<script>
    document.getElementById('test-btn').addEventListener('click', () => {
        const formData = new FormData();
        formData.append('test_input', 'Hello from JS!');

        fetch('/test', {
            method: 'POST',
            body: formData
        })
        .then(async response => {
            const respJson = await response.json();
            document.getElementById('response').innerHTML = respJson.message;
        });
    });
</script>
</body>
</html>

On browser when I click on "Test" button, I see "Hello from JS!".

When I execute the PEST test

it('test js fetch', function () {
    $page = visit('/test');

    $page->click('Test')
        ->assertSee('Hello from JS!')
        ->screenshot();
});

The test fails with the following message:

 FAILED  Tests\Browser\TestTest > it test js fetch                                                                                                                                                                                                                                                       
  Expected to see text [Hello from JS!] on the page initially with the url [http://php:40811/test], but it was not found or not visible. A screenshot of the page has been saved to [Tests/Browser/Screenshots/it_test_js_fetch].

  at tests/Browser/TestTest.php:7
      3▕ it('test js fetch', function () {
      4▕     $page = visit('/test');
      5▕ 
      6▕     $page->click('Test')
  ➜   7▕         ->assertSee('Hello from JS!')
      8▕         ->screenshot();
      9▕ });
     10▕ 

In the screenshot I see: "No input provided".

Does anyone knows what is the cause of this issue?

The issue can be reproduced in this repository

[costiiordan]

I have found the problem.
The issue is in pest-plugin-browser package. It does not support multipart form requests.
There is a PR that tries to solve this issue.
I hope it get's merged and released soon.