anchor.diff:              (setf seen c)))
         (is (eql seen child)))))
   
  -(test root-attach-dettach-child
  +(test (root-attach-dettach-child :depends-on root-with-no-children)
     (let ((root (make-instance 'component))
            (child (make-instance 'component)))
       (is (not (parent child)))
  
positive.code:     (is (= (array-dimension (children root) 0) 2))
      (is (eql (aref (children root) 0) child1))
      (is (eql (aref (children root) 1) child2))))
  
negative.code:     (is (arrayp (children root)))
      (is (zerop (array-dimension (children root) 0)))))
  
  (test (root-with-one-child :depends-on root-with-no-children)
    (let* ((root (make-instance 'component))
           (child (make-instance 'component :parent root)))
      (is (eql root (parent child)))
  