test: remove meaningless test

See #8069 (comment)

Author: kenjis

tests/system/Test/TestCaseTest.php

@@ -13,8 +13,6 @@
 
 use CodeIgniter\CLI\CLI;
 use CodeIgniter\Events\Events;
-use CodeIgniter\HTTP\Response;
-use Config\App;
 use Tests\Support\Test\TestForReflectionHelper;
 
 /**
@@ -74,31 +72,6 @@ public function testStreamFilter(): void
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    /**
-     * PHPunit emits headers before we get nominal control of
-     * the output stream, making header testing awkward, to say
-     * the least. This test is intended to make sure that this
-     * is happening as expected.
-     *
-     * TestCaseEmissionsTest is intended to circumvent PHPunit,
-     * and allow us to test our own header emissions.
-     */
-    public function testPHPUnitHeadersEmitted(): void
-    {
-        $response = new Response(new App());
-        $response->pretend(true);
-
-        $body = 'Hello';
-        $response->setBody($body);
-
-        ob_start();
-        $response->send();
-        ob_end_clean();
-
-        $this->assertHeaderEmitted('Content-type: text/html;');
-        $this->assertHeaderNotEmitted('Set-Cookie: foo=bar;');
-    }
-
     public function testCloseEnough(): void
     {
         $this->assertCloseEnough(1, 1);