IBM/node-celery-ts

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import { ResultMessage } from "./messages";
import { ResultBackend } from "./result_backend";

/**
 * A dummy backend. All operations will either throw or return a rejected
 * `Promise`, whichever is appropriate. To be used when ignoring results.
 */
export class NullBackend implements ResultBackend {
    /**
     * @returns A `NullBackend` ready to fail at the earliest convenience.
     */
    public constructor() { }

    /**
     * @returns A rejected `Promise`.
     */
    public async put(): Promise<string> {
        throw new Error("cannot put results onto a null backend");
    }

    /**
     * @returns A rejected `Promise`.
     */
    public async get<T>(): Promise<ResultMessage<T>> {
        throw new Error("cannot get results from a null backend");
    }

    /**
     * @returns A rejected `Promise`.
     */
    public delete(): Promise<string> {
        throw new Error("cannot delete results from a null backend");
    }

    /**
     * @returns A resolved `Promise`.
     */
    public async disconnect(): Promise<void> {
        await this.end();
    }

    /**
     * @returns A resolved `Promise`.
     */
    public async end(): Promise<void> { }

    /**
     * @returns Nothing; will never return.
     * @throws Error If invoked.
     */
    public uri(): never {
        throw new Error("cannot query the URI of a null backend");
    }
}