将摩卡“done()”转换为“done()”测试“异步”当“完成()”时在内部函数中调用

发布于 2025-01-11 00:07:39 字数 1076 浏览 0 评论 0原文

我想在下面的测试中添加对同步函数的调用：

describe('the server', function() {
  it('should respond to a udp packet', function(done) {

    // TODO: call async function here

    const udp = dgram.createSocket('udp4');

    udp.on('error', function(error) {
      console.log(error);
    });

    udp.on('message', function(msg, rinfo) {
      console.log('msg', msg);
      console.log('rinfo', rinfo);
      // TODO: check the reply
      udp.close();
      done();
    });
    udp.bind();

    // send a request
    const bytes = Buffer.from("421a0800117860bc457f0100001a0653455256455222054d54303031", 'hex');
    udp.send(bytes, SERVER_PORT, SERVER_ADDR)
  });
});

如果我只是添加 async, 来使：

it('should respond to a udp packet', async function(done) {

我收到错误：

1) the server
     should respond to a udp packet:
   Error: Resolution method is overspecified. Specify a callback *or* return a Promise; not both.

但我需要 done 作为仅当从服务器收到数据包时测试才结束。

有没有一种方法只能从内部函数内部的异步函数“返回”？

原文

I would like to add a call to a sync function to the test below:

describe('the server', function() {
  it('should respond to a udp packet', function(done) {

    // TODO: call async function here

    const udp = dgram.createSocket('udp4');

    udp.on('error', function(error) {
      console.log(error);
    });

    udp.on('message', function(msg, rinfo) {
      console.log('msg', msg);
      console.log('rinfo', rinfo);
      // TODO: check the reply
      udp.close();
      done();
    });
    udp.bind();

    // send a request
    const bytes = Buffer.from("421a0800117860bc457f0100001a0653455256455222054d54303031", 'hex');
    udp.send(bytes, SERVER_PORT, SERVER_ADDR)
  });
});

If I just add async, to make:

it('should respond to a udp packet', async function(done) {

I get an error:

1) the server
     should respond to a udp packet:
   Error: Resolution method is overspecified. Specify a callback *or* return a Promise; not both.

but I need the done as the test is only over when a packet is received from the server.

Is there a way of only "returning" from an async function from within an inner function?

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暖阳 2025-01-18 00:07:39

这里至少有两种方法：使用异步调用返回的 Promise 或使整个测试函数异步。我将展示第二种方法，因为在不知道待办事项中的异步函数调用是什么样子的情况下，它更容易实现。

基本上需要完成三项更改：

使测试函数异步并删除 done 参数。
将使用 done 回调的语句或语句组包装在 Promise 中。如果您想保留该名称，请将 Promise 回调的第一个参数命名为 done。
返回承诺。

describe('the server', function() {
  it('should respond to a udp packet', async function() {

    // TODO: call async function here

    const udp = dgram.createSocket('udp4');

    udp.on('error', function(error) {
      console.log(error);
    });

    const promise = new Promise(done => {
      udp.on('message', function(msg, rinfo) {
        console.log('msg', msg);
        console.log('rinfo', rinfo);
        // TODO: check the reply
        udp.close();
        done();
      });
    });

    udp.bind();

    // send a request
    const bytes = Buffer.from("421a0800117860bc457f0100001a0653455256455222054d54303031", 'hex');
    udp.send(bytes, SERVER_PORT, SERVER_ADDR);
    return promise;
  });
});

这对于测试来说应该足够了。为了更准确地处理错误，您可能希望在出现异常时拒绝承诺：

const promise = new Promise((done, reject) => {
    try {
      udp.on('message', function(msg, rinfo) {
      console.log('msg', msg);
      console.log('rinfo', rinfo);
      // TODO: check the reply
      udp.close();
    } catch (err) {
      reject(err);
      return;
    }
    done();
  });
});

There are at least two approaches here: work with the promise returned by the async call or make the whole test function async. I'm going to show the second method becuase it's easier to implement without knowing how the async function call in the todo looks like.

There are basically three changes to be done:

Make the test function async and remove the done parameter.
Wrap the statement or group of statements that use the done callback in a promise. Name the first parameter of the promise callback done if you want to keep that name.
return the promise.

describe('the server', function() {
  it('should respond to a udp packet', async function() {

    // TODO: call async function here

    const udp = dgram.createSocket('udp4');

    udp.on('error', function(error) {
      console.log(error);
    });

    const promise = new Promise(done => {
      udp.on('message', function(msg, rinfo) {
        console.log('msg', msg);
        console.log('rinfo', rinfo);
        // TODO: check the reply
        udp.close();
        done();
      });
    });

    udp.bind();

    // send a request
    const bytes = Buffer.from("421a0800117860bc457f0100001a0653455256455222054d54303031", 'hex');
    udp.send(bytes, SERVER_PORT, SERVER_ADDR);
    return promise;
  });
});

This should be sufficient for a test. For a more accurate error handling you may want to reject the promise in case of an exception:

const promise = new Promise((done, reject) => {
    try {
      udp.on('message', function(msg, rinfo) {
      console.log('msg', msg);
      console.log('rinfo', rinfo);
      // TODO: check the reply
      udp.close();
    } catch (err) {
      reject(err);
      return;
    }
    done();
  });
});

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