fix: [CURLRequest] Multiple HTTP 100 return by API.

[ping-yee]

Description
Closes #8347

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

Since you were able to reproduce the issue, can you also provide a test case for this scenario? Thanks!

[ping-yee]

@michalsn I'm afraid I can't do that, as this seems like a specific error that occurs when using a Python framework.

To write a test case for this scenario, we would need to set up a Flask API service in advance, which I don't think is a good direction.

However, I can provide the code I used when reproducing the issue.

Reproduce

In CI4

<?php

namespace App\Controllers;

use CodeIgniter\API\ResponseTrait;

class Home extends BaseController
{
    use ResponseTrait;

    public function index()
    {
        $client = \Config\Services::curlrequest();

        try {
            $options = [
                'headers' => [
                    'Expect' => '100-continue'
                ],
                'debug'   => true,
            ];

            $response = $client->request('GET', 'http://localhost:5000', $options);
            // We'll get 100 until we fix it.
            // After modification we will get 200.
            dd($response->getStatusCode());
        } catch (\Exception $e) {
            echo "Request failed: " . $e->getMessage();
        }
    }
}

In flask

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/')
def hello_world():
    return jsonify(message="Hello, World!")

if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0', port=5000)

Also, you can get the repeat response by using curl command.

curl localhost:5000 -v -H "Expect: 100-continue"

user@Py:/mnt/d/CodeIgniter4$ curl localhost:5000 -v -H "Expect: 100-continue" 
*   Trying 127.0.0.1:5000...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 5000 (#0)
> GET / HTTP/1.1
> Host: localhost:5000
> User-Agent: curl/7.68.0
> Accept: */*
> Expect: 100-continue
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 100 Continue
* Mark bundle as not supporting multiuse
< HTTP/1.1 100 Continue
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Server: Werkzeug/2.2.2 Python/3.7.17
< Date: Sun, 28 Jan 2024 06:05:36 GMT
< Content-Type: application/json
< Content-Length: 33
< Connection: close
<
{
  "message": "Hello, World!"
}
* Closing connection 0

[michalsn]

We don't need Flask. We tested output before, like here: https://github.com/codeigniter4/CodeIgniter4/blob/develop/tests/system/HTTP/CURLRequestTest.php#L385

[kenjis]

We use MockCURLRequest for testing:

CodeIgniter4/tests/system/HTTP/CURLRequestTest.php

Line 49 in d72a893

return new MockCURLRequest(($app), $uri, new Response($app), $options);

[ping-yee]

@michalsn @kenjis thank you for your explanation!
I have added the test case, review please.