public function testAppendChildToElementThrowsError()
 {
     $this->setExpectedException('Saml\\Ecp\\Soap\\Exception\\AppendChildException');
     $child = $this->_getDomElementMock();
     $element = $child = $this->_getDomElementMock();
     $element->expects($this->once())->method('appendChild')->with($child)->will($this->throwException(new \DomException()));
     $this->_message->appendChildToElement($element, $child);
 }