What is the test for a plaintiff to sue for damages under the tort theory of wrongful interference with contractual rights?

5 The reason was stated in Dryden v. Tri-Valley Growers, supra, 65 Cal.App.3d at 999, 135 Cal.Rptr. 720: "It is obvious that if an action is brought for interference with contractual relationship by one party to a contract against another who is also a party to that same contract, the grievance of the plaintiff is, in essence, breach of contract; and, in such case, plaintiff is entitled to recover all damages flowing from the breach. In such an instance to allow the plaintiff to sue under the tort theory of wrongful interference with contractual rights would not only be superfluous, but also would enable him to recover tort damages (e.g., punitive damages, damages for mental suffering) to which he is not entitled under California law."