I’m trying to write a unit test for a PHP script that does not contain any functions or classes.
It is just a plain PHP script that returns header('Location: ${url}') when a specific condition is met.

<?php
error_reporting(0);
include XOOPS_ROOT_PATH . "/include/curl/functions.php";
include "ADBConnection.php";
include "MDBConnection.php";

global $user;
if (!empty($user) && is_object($user)) {

    $a_connection = new ADBConnection();
    $m_conn = new MDBConnection();
    $conn = $a_connection->getConnection();
    $a_connection->setSqlQuery($some_sql);

   $prepare = $conn->prepare($db_connection->getSqlQuery());
   $prepare->execute([
       "user_id" => $user->customer_id(),
   ]);
   $result = $prepare->fetchAll();

   $is_allow = false;
   if (!empty($result)) {
      foreach ($result as $item) {
          if ($item['is_allow'] > 0) {
              $is_allow = true;
              break;
          }
      }
   }

  $user_admin = $m_conn->getUserAdmin($user->uid());
  if ($is_allow || $user_admin === true) {
      header("Location: ${some_url}");
  } else {
    header("Location: ${another_some_url}");
  }
} else {
  header("Location: /");
}

Below is what I’ve tried to write a test case for that script file.

protected function setUp()
{
    parent::setUp();

    $this->userMock = $this->getMockBuilder(User::class)
        ->setMethods(['customer_id', 'uid'])
        ->getMock();

    $this->axDatabaseMock = $this->getMockBuilder(ADBConnection::class)
        ->setMethods()
        ->getMock();

    $this->marcDatabaseMock = $this->getMockBuilder(MDBConnection::class)
        ->setMethods(['getUserAdmin'])
        ->getMock();
}

public function test_redirect_user_to_some_url_page()
{

    $this->userMock->method('customer_id')
        ->willReturn(1);
    $this->userMock->method('uid')
        ->willReturn(1);

    $this->marcDatabaseMock->method('getUserAdmin')
        ->willReturn(true);

    ob_start();
    require('path_to_script');
    $headers = xdebug_get_headers();
    $this->assertContains('Location: ${some_url}', $headers);
}

When I tried to debug the returned value of $headers it gave me this:

array(1) {
  [0] =>
  string(38) "Content-type: text/html; charset=UTF-8"
}

It seems like it does not return an expected result.
So how can we write unit test for a PHP file script?

I also checked with other answers but didn’t figure it out.