What is the test for estoppel in the context of a cause of action?

This broader definition of cause of action estoppel recognizes that parties to an action have a duty to bring their whole case to the court’s attention and not to reserve some aspect of the matter against the possibility of a decision in the opponent’s favour as a means of preserving a way to come at the opponent again. As Wigram V.C. explained in Henderson v. Henderson (1843), 3 Hare 100 at 114-15, 67 E.R. 313 at 319: In trying this question I believe I state the rule of the court correctly when I say that, where a given matter becomes the subject of litigation in, and of adjudication by, a court of competent jurisdiction, the court requires the parties to that litigation to bring forward their whole case, and will not (except under special circumstances) permit the same parties to open the same subject of litigation in respect of the matter which might have been brought forward as part of the subject in contest, but which was not brought forward, only because they have, from negligence, inadvertence, or even accident, omitted part of their case. The plea of res judicata applies, except in special cases, not only to points upon which the court was actually required by the parties to form an opinion and pronounce a judgment, but to every point which properly belonged to the subject of litigation, in which the parties exercising reasonable diligence, might have brought forward at the time.