How to test for expected headers?

Question

I have a unit test that fails because headers are already sent. However, the header in this scenario is expected.

How do I tell PHPUnit to expect a 500 header?

I've read this question but it didn't help.

The method is wrapped inside an output buffer.

ob_start();
$foo->methodWhichSendsHeader();
ob_clean();

Answer 1

Another possible approach is to override the header php function for the namespace you are testing. https://www.codepunker.com/blog/overwrite-built-in-php-functions-using-namespaces

namespace My\Application\Namespace;
use My\Test\Application\Namespace;    

//this overrides the header function for that namespace
//it works only if the function is called without the backslash
function header($string){
    HeaderCollector::$headers[] = $string;
}

namespace My\Test\Application\Namespace

/**
 * Class HeaderCollector
 * Using this in combination with function header override
 * for the namespace My\Application\Namespace
 * we can make assertions on headers sent
 */
class HeaderCollector {

    public static $headers = [];

    //call this in your test class setUp so headers array is clean before each test
    public static function clean() {
        self::$headers = [];
    }
}

Then in your test class

namespace My\Test\Application\Namespace
use PHPUnit\Framework\TestCase;


class MyTest extends TestCase {

    protected function setUp() {
        parent::setUp();
        //clean for each test
        HeaderCollector::clean();
    }

    public function testHeaders() {
        //call the code that send headers
        ...

        self::assertEquals(
            ["Content-Type: text/html; charset=UTF-8", "Another-Header..."],
            HeaderCollector::$headers
        );
    }
}

You can keep your code clean and you don't need xdebug