export type MathFns = {
    add(a: number, b: number): Promise<number>;
    mul(a: number, b: number): Promise<number>;
};
export declare function setupMathSpy(): {
    calls: {
        add: {
            a: number;
            b: number;
            ret: number;
        }[];
        mul: {
            a: number;
            b: number;
            ret: number;
        }[];
    };
    fns: MathFns;
};