What is the test for a federal district court to abstain from exercising jurisdiction in a criminal case?

A district court must abstain from exercising jurisdiction where: "(1) state judicial proceedings are pending; (2) the state proceedings involve important state interests; and (3) the state proceedings afford the federal plaintiff an adequate opportunity to litigate federal constitutional claims." Id. (setting forth criteria for abstention under Younger v. Harris, 401 U.S. 37 (1971)). The court "should not act to restrain a criminal prosecution, when the moving party has an adequate remedy at law and will not suffer irreparable injury if denied equitable relief." Younger, 401 U.S. at 43.