/**
 * Make an object or array recursively immutable.
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze.
 */
export declare function deepFreeze<T>(object: T): T;
export declare function expect_rejects_toThrow(expression: any, errorMessage?: string): Promise<void>;
export declare function expect_not_toThrow(fn: () => void, errorMessage?: string): void;
export declare function expect_toThrow(fn: () => void, errorMessage?: string): void;
//# sourceMappingURL=utils.d.ts.map