http_client_middleware service throws exception in Functional test

Problem/Motivation

I have a Functional test in a custom module which test a feeds response. For this I am intercepting the original api call to provide test data and to intercept call I am using a custom service in a test module with that service tagged as http_client_middleware .

it worked fine with 200 response but throws exception with 403 response

Steps to reproduce

Below is the files I have created
Test file - docroot/modules/custom/feed_custom/tests/src/Functional/FeaturesTest.php

<?php

namespace Drupal\Tests\feed_custom\Functional;

use Drupal\Tests\BrowserTestBase;

/**
 * Test for specific features.
 *
 * @group feed_custom
 */
class FeaturesTest extends BrowserTestBase {
  /**
   * {@inheritdoc}
   */
  protected static $modules = [
    'feed_custom',
    'feed_test',
    'dblog',
  ];

  /**
   * {@inheritdoc}
   */
  protected function setUp(): void {
    parent::setUp();

  }

  /**
   * Testing the download and import of the custom feed.
   */
  protected function testFeedImport(): void {

    // Set the test data into a state variable.
    $file_path = $this->container->get('extension.path.resolver')->getPath('module', 'feed_custom') . '/tests/fixtures/test_data.json';
    \Drupal::state()->set('feed_custom.test_data', file_get_contents($file_path));
    
// Also set the status code into its own state variable.
    \Drupal::state()->set('feed_custom.status_code', 200);

    // Run Cron (which will run the feed import).
    \Drupal::service('cron')->run();

    // Set the test_data state variable to null.
    // This will replicate the feed returning nothing with a 200 status code.
    \Drupal::state()->set('feed_custom.test_data', NULL);

    // Run cron again.
    // This should hit our "no data returned" message in feed_custom_cron().
    \Drupal::service('cron')->run();

    // Now lets try to replicate a 403 error.
    \Drupal::state()->set('feed_custom.status_code', 403);

    // Run cron again.
    // This will hit our other error message related to a 403.
    \Drupal::service('cron')->run();
  }

}

feed_custom/tests/modules/feed_test/feed_test.services.yml

services:
  feed_test.http_client_middleware:
    class: Drupal\feed_test\TestHttpClientMiddleware
    arguments: ['@state']
    tags:
      - { name: http_client_middleware }

docroot/modules/custom/feed_custom/tests/modules/feed_test/src/TestHttpClientMiddleware.php

<?php

namespace Drupal\feed_test;

use Drupal\Core\State\StateInterface;
use GuzzleHttp\Promise\FulfilledPromise;
use GuzzleHttp\Promise\PromiseInterface;
use GuzzleHttp\Psr7\Response;
use Psr\Http\Message\RequestInterface;

/**
 * Overrides the requested endpoint when running tests.
 */
class TestHttpClientMiddleware {

  /**
   * Constructs a new instance.
   *
   * @param \Drupal\Core\State\StateInterface $state
   *   The state.
   */
  public function __construct(protected StateInterface $state) {
  }

  /**
   * Invoked method that returns a promise with test data.
   */
  public function __invoke(): \Closure {
    return function ($handler) {
      return function (RequestInterface $request, array $options) use ($handler): PromiseInterface {
        // API requests to feed.
        if (str_contains($request->getUri(), 'https://test.qweb.com')) {
          return $this->createPromise($request);
        }
        // Otherwise, no intervention. We defer to the handler stack.
        return $handler($request, $options);
      };
    };
  }

  /**
   * Creates a promise for the request.
   */
  protected function createPromise(RequestInterface $request): PromiseInterface {
    $response = new Response($this->state->get('feed_custom.status_code'), [], $this->state->get('feed_custom.test_data'));
    return new FulfilledPromise($response);
  }

}

Here in the createPromise() function when value of $this->state->get('feed_custom.status_code') is 200 it works fine but when value of $this->state->get('feed_custom.status_code') is other than 200 it throws exception as below

GuzzleHttp\Exception\ClientException: Client error: `Get https://test.qweb.com/getData` resulted in a `403 Forbidden` response in GuzzleHttp\Exception\RequestException::create() (line 113 of /vendor/guzzlehttp/guzzle/src/Exception/RequestException.php).

Any suggestions/help would be greatly appreciated!

Proposed resolution

Remaining tasks

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