private function compareNodes( $expectedNav, $generatedNav )
	{
		if ( is_null( $this->comparer ) )
		{
			// $this->comparer = new TreeComparer( null );
			$this->comparer = new ContextComparer( null );
			$this->comparer->excludeWhitespace = true;
		}

		return $this->comparer->DeepEqualByNavigator( $expectedNav , $generatedNav );
	}