What is the test for a motion to dismiss an action for failure to state a claim?

We review de novo the district court's dismissal of the action for failure to state a claim. Klarfeld v. United States, 944 F.2d 583, 585 (9th Cir.1991), reh'g en banc denied, 962 F.2d 866 (9th Cir.1992). In evaluating a Rule 12(b)(6) motion, we accept all material allegations in the complaint as true, and construe them in the light most favorable to plaintiff. Id. Only if plaintiff " 'can prove no set of facts in support of his claim which would entitle him to relief' " is dismissal warranted. Id. (quoting Gibson v. United States, 781 F.2d 1334, 1337 (9th Cir.1986), cert. denied, 479 U.S. 1054, 107 S.Ct. 928, 93 L.Ed.2d 979 (1987)).