export declare function spy<P extends Array<unknown>, R>(closure: (...p: P) => R): Spyer<P, R>;
export declare class Spyer<P extends Array<unknown>, R> {
    readonly closure: (...p: P) => R;
    constructor(closure: (...p: P) => R);
    readonly calls: Call<P, R>[];
    call(...params: P): R;
}
export declare class Call<P extends Array<unknown>, R> {
    readonly params: P;
    readonly result: R;
    readonly time: Date;
    constructor(params: P, result: R, time?: Date);
}