public function testHeadAttributes()
 {
     $page = new SeoPage();
     $page->setHeadAttributes(array('head1' => 'value1'));
     $page->addHeadAttribute('head2', 'value2');
     $expected = array('head1' => 'value1', 'head2' => 'value2');
     $this->assertEquals($expected, $page->getHeadAttributes());
     $this->assertTrue($page->hasHeadAttribute('head1'));
     $page->removeHeadAttribute('head1');
     $this->assertFalse($page->hasHeadAttribute('head1'));
 }