Test PHP headers with PHPUnit

I'm trying to use PHPunit to test a class that outputs some custom headers.

The problem is that on my machine this:

<?php

class HeadersTest extends PHPUnit_Framework_TestCase {

    public function testHeaders()
    {
        ob_start();

        header('Location: foo');
        $headers_list = headers_list();
        header_remove();

        ob_clean();

        $this->assertContains('Location: foo', $headers_list);
    }
}

or even this:

<?php

class HeadersTest extends PHPUnit_Framework_TestCase {

    public function testHeaders()
    {
        ob_start();

        header('Location: foo');
        header_remove();

        ob_clean();
    }
}

return this error:

name@host [~/test]# phpunit --verbose HeadersTest.php 
PHPUnit 3.6.10 by Sebastian Bergmann.

E

Time: 0 seconds, Memory: 2.25Mb

There was 1 error:

1) HeadersTest::testHeaders
Cannot modify header information - headers already sent by (output started at /usr/local/lib/php/PHPUnit/Util/Printer.php:173)

/test/HeadersTest.php:9

FAILURES!
Tests: 1, Assertions: 0, Errors: 1.

This looks as if there is something else outputting to the terminal before the test runs even though there is no other file included and there is no other character before the beginning of the PHP tag. Could it be something inside PHPunit that is causing this?

What could the issue be?

The issue is that PHPUnit will print a header to the screen and at that point you can't add more headers.

The work around is to run the test in an isolated process. Here is an example

<?php

class FooTest extends PHPUnit_Framework_TestCase
{
    /**
     * @runInSeparateProcess
     */
    public function testBar()
    {
        header('Location : http://foo.com');
    }
}

This will result in:

$ phpunit FooTest.php
PHPUnit 3.6.10 by Sebastian Bergmann.

.

Time: 1 second, Memory: 9.00Mb

OK (1 test, 0 assertions)

The key is the @runInSeparateProcess annotation.

If you are using PHPUnit ~4.1 or something and get the error:

PHP Fatal error:  Uncaught Error: Class 'PHPUnit_Util_Configuration' not found in -:378
Stack trace:
#0 {main}
  thrown in - on line 378

Fatal error: Uncaught Error: Class 'PHPUnit_Util_Configuration' not found in - on line 378

Error: Class 'PHPUnit_Util_Configuration' not found in - on line 378

Call Stack:
    0.0013     582512   1. {main}() -:0

Try add this to your bootstrap file to fix it:

<?php
if (!defined('PHPUNIT_COMPOSER_INSTALL')) {
    define('PHPUNIT_COMPOSER_INSTALL', __DIR__ . '/path/to/composer/vendors/dir/autoload.php');
}