anchor.diff:      (is (not (parent child)))
       (is (zerop (array-dimension (children root) 0)))))
   
  -(test root-with-two-children
  +(test (root-with-two-children :depends-on root-with-one-child)
     (let* ((root (make-instance 'component))
            (child1 (make-instance 'component :parent root :depth 1))
            (child2 (make-instance 'component :parent root :depth -1)))
  
positive.code:             (setf seen c)))
        (is (eql seen child)))))
  
  (test root-attach-dettach-child
    (let ((root (make-instance 'component))
           (child (make-instance 'component)))
      (is (not (parent child)))
  
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)))
  