There is one other guideline to participating in a group conversation ... read
all the e-mails on the subject before replying.

Certainly, we all forget this on occasions, but the e-mail to which you are
replying was posted ten days ago, and there was an interchange that went on over
a period of days. I have nine messages saved in my archive and that's only a
portion of the interchange.

I think you will find that your suggestion is very similar to one I posted on
January 12. The constructor of C already gets the instance of A, so could use
it to call  A's "test". B doesn't need a reference to A in order to use "test".