Unit Testing with items that need to send headers

Well, your session manager is basically broken by design. To be able to test something, it must be possible to isolate it from side effects. Unfortunately, PHP is designed in such a way, that it encourages liberal use of global state (echo, header, exit, session_start etc. etc.).

The best thing you can do, is to isolate the side-effects in a component, that can be swapped at runtime. That way, your tests can use mocked objects, while the live code uses adapters, that have real side-effects. You'll find that this doesn't play well with singletons, which I presume you're using. So you'll have to use some other mechanism for getting shared objects distributed to your code. You can start with a static registry, but there are even better solutions if you don't mind a bit of learning.

If you can't do that, you always have the option of writing integration-tests. Eg. use the PHPUnit's equivalent of WebTestCase.

Create a bootstrap file for phpunit, which calls:

session_start();

Then start phpunit like this:

phpunit --bootstrap pathToBootstrap.php --anotherSwitch /your/test/path/

The bootstrap file gets called before everything else, so the header hasn't been sent and everything should work fine.

phpUnit prints output as the tests run thus causing headers_sent() to return true even in your first test.

To overcome this issue for an entire test suite you simply need to use ob_start() in your setup script.

For example, say you have a file named AllTests.php that is the first thing loaded by phpUnit. That script might look like the following:

<?php

ob_start();

require_once 'YourFramework/AllTests.php';

class AllTests {
    public static function suite() {
        $suite = new PHPUnit_Framework_TestSuite('YourFramework');
        $suite->addTest(YourFramework_AllTests::suite());
        return $suite;
    }
}