silverstripe-cms/tests/controller/ContentControllerSearchExtensionTest.php

<?php
class ContentControllerSearchExtensionTest extends SapphireTest {
	
	public function testCustomSearchFormClassesToTest() {
		FulltextSearchable::enable('File');
		
		$page = new Page();
		$page->URLSegment = 'whatever';
		$page->Content = 'oh really?';
		$page->write();
		$page->publish('Stage', 'Live'); 
		$controller = new ContentController($page);
		$form = $controller->SearchForm(); 
		
		if (get_class($form) == 'SearchForm') $this->assertEquals(array('File'), $form->getClassesToSearch());
	}
}