What is the test for dismissing a state claim against a federal defendant?

"Its justification lies in considerations of judicial economy, convenience and fairness to litigants; if these are not present a federal court should hesitate to exercise jurisdiction over state claims, even though bound to apply state law to them . . .. Needless decisions of state law should be avoided both as a matter of comity and to promote justice between the parties, by procuring for them a surer-footed reading of applicable law. Certainly, if the federal claims are dismissed before trial, even though not insubstantial in a jurisdictional sense, the state claims should be dismissed as well. Similarly, if it appears that the state issues substantially predominate, whether in terms of proof, of the scope of the issues raised, or of the comprehensiveness of the remedy sought, the state claims may be dismissed without prejudice and left for resolution to state tribunals." (383 U.S. at 726-727, 86 S.Ct. at 1139; footnote numerals and footnotes omitted.)

See also Almenares v. Wyman, 2d Cir. 1971, 453 F.2d 1075, 1083-1084.