diff --git a/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/CurlTest.php b/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/CurlTest.php
index 17b88e398230e..22fed9cfc7467 100644
--- a/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/CurlTest.php
+++ b/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/CurlTest.php
@@ -26,4 +26,57 @@ public function testInvalidProtocol()
         $client = new Curl();
         $client->get('telnet://127.0.0.1/test');
     }
+
+    /**
+     * Check the HTTP client ability to parse headers case-insensitive.
+     */
+    public function testParseHeaders()
+    {
+        // Prepare protected parseHeaders method
+        $curl = new Curl();
+        $parseHeaders = new \ReflectionMethod(
+            $curl,
+            'parseHeaders'
+        );
+        $parseHeaders->setAccessible(true);
+
+        // Parse headers
+        foreach ($this->headersDataProvider() as $header) {
+            $parseHeaders->invoke($curl, null, $header);
+        }
+
+        // Validate headers
+        $headers = $curl->getHeaders();
+        $this->assertIsArray($headers);
+        $this->assertEquals([
+            'Content-Type' => 'text/html; charset=utf-8',
+            'Set-Cookie' => [
+                'Normal=OK',
+                'Uppercase=OK',
+                'Lowercase=OK',
+            ]
+        ], $headers);
+
+        // Validate status
+        $status = $curl->getStatus();
+        $this->assertIsInt($status);
+        $this->assertEquals(200, $status);
+
+        // Validate cookies
+        $cookies = $curl->getCookies();
+        $this->assertIsArray($cookies);
+        $this->assertEquals([
+            'Normal' => 'OK',
+            'Uppercase' => 'OK',
+            'Lowercase' => 'OK',
+        ], $cookies);
+    }
+
+    /**
+     * @return array
+     */
+    public function headersDataProvider()
+    {
+        return array_filter(explode(PHP_EOL, file_get_contents(__DIR__ . '/_files/curl_headers.txt')));
+    }
 }
diff --git a/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/_files/curl_headers.txt b/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/_files/curl_headers.txt
new file mode 100644
index 0000000000000..48a2d6fbcf0b7
--- /dev/null
+++ b/lib/internal/Magento/Framework/HTTP/Test/Unit/Client/_files/curl_headers.txt
@@ -0,0 +1,5 @@
+Status: 200 OK
+Content-Type: text/html; charset=utf-8
+Set-Cookie: Normal=OK
+SET-COOKIE: Uppercase=OK
+set-cookie: Lowercase=OK
diff --git a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/CurlMockTest.php b/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/CurlMockTest.php
deleted file mode 100644
index bf386a2387d71..0000000000000
--- a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/CurlMockTest.php
+++ /dev/null
@@ -1,86 +0,0 @@
-<?php
-/**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
- */
-
-declare(strict_types=1);
-
-namespace Magento\Framework\HTTP\Test\Unit\ClientMock;
-
-use Magento\Framework\HTTP\Test\Unit\ClientMock\Mock\CurlMock;
-use PHPUnit\Framework\TestCase;
-
-/**
- * Test HTTP client based on cUrl (mocked curl_exec).
- */
-class CurlMockTest extends TestCase
-{
-    /**
-     * @var CurlMock
-     */
-    protected $model;
-
-    /**
-     * @var \Closure
-     */
-    public static $curlExectClosure;
-
-    protected function setUp(): void
-    {
-        require_once __DIR__ . '/_files/curl_exec_mock.php';
-        $this->model = new CurlMock();
-    }
-
-    /**
-     * Handle Curl response
-     *
-     * @param string $response
-     * @return string
-     */
-    private function handleResponse(string $response): string
-    {
-        // Make sure we use valid newlines
-        $response = explode("\r\n\r\n", str_replace("\n", "\r\n", $response), 2);
-
-        // Parse headers
-        $headers = explode("\r\n", $response[0]);
-        foreach ($headers as $header) {
-            call_user_func([$this->model, 'parseHeaders'], $this->model->getResource(), $header);
-        }
-
-        // Return body
-        return $response[1] ?? '';
-    }
-
-    /**
-     * Check that HTTP client parses cookies.
-     *
-     * @param string $response
-     * @dataProvider cookiesDataProvider
-     */
-    public function testCookies($response)
-    {
-        self::$curlExectClosure = function () use ($response) {
-            $this->handleResponse($response);
-        };
-        $this->model->get('http://127.0.0.1/test');
-        $cookies = $this->model->getCookies();
-        $this->assertIsArray($cookies);
-        $this->assertEquals([
-            'Normal' => 'OK',
-            'Uppercase' => 'OK',
-            'Lowercase' => 'OK',
-        ], $cookies);
-    }
-
-    /**
-     * @return array
-     */
-    public function cookiesDataProvider()
-    {
-        return [
-            [file_get_contents(__DIR__ . '/_files/curl_response_cookies.txt')],
-        ];
-    }
-}
diff --git a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/Mock/CurlMock.php b/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/Mock/CurlMock.php
deleted file mode 100644
index 03d786a7ec73c..0000000000000
--- a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/Mock/CurlMock.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-/**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
- */
-declare(strict_types=1);
-
-namespace Magento\Framework\HTTP\Test\Unit\ClientMock\Mock;
-
-use Magento\Framework\HTTP\Client\Curl;
-
-/**
- * Extended Curl class with modifications for testing
- */
-class CurlMock extends Curl
-{
-    // @codingStandardsIgnoreStart
-    /**
-     * Unfortunately, it is necessary for the tests to set this function public.
-     *
-     * @param resource $ch curl handle, not needed
-     * @param string $data
-     * @return int
-     * @throws \Exception
-     */
-    public function parseHeaders($ch, $data)
-    {
-        return parent::parseHeaders($ch, $data);
-    }
-    // @codingStandardsIgnoreEnd
-
-    /**
-     * Return Curl resource, only used for testing.
-     *
-     * @return resource
-     */
-    public function getResource()
-    {
-        return $this->_ch;
-    }
-}
diff --git a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/_files/curl_exec_mock.php b/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/_files/curl_exec_mock.php
deleted file mode 100644
index 019f4889530d8..0000000000000
--- a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/_files/curl_exec_mock.php
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-/**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
- */
-declare(strict_types=1);
-
-namespace Magento\Framework\HTTP\Client;
-
-use Magento\Framework\HTTP\Test\Unit\ClientMock\CurlMockTest;
-
-/**
- * Override global PHP function
- *
- * @SuppressWarnings("unused")
- * @param mixed $resource
- * @return string
- */
-function curl_exec($resource)
-{
-    return call_user_func(CurlMockTest::$curlExectClosure);
-}
diff --git a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/_files/curl_response_cookies.txt b/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/_files/curl_response_cookies.txt
deleted file mode 100644
index d68d286bb4de8..0000000000000
--- a/lib/internal/Magento/Framework/HTTP/Test/Unit/ClientMock/_files/curl_response_cookies.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-HTTP/1.1 200 OK
-Server: Apache
-X-Frame-Options: SAMEORIGIN
-Strict-Transport-Security: max-age=14400
-Strict-Transport-Security: max-age=14400
-Content-Type: text/html; charset=UTF-8
-Date: Mon, 22 Apr 2013 09:52:36 GMT
-Content-Length: 8
-Connection: keep-alive
-Set-Cookie: Normal=OK
-SET-COOKIE: Uppercase=OK
-set-cookie: Lowercase=OK
-
-VERIFIED