Node.js 什么'；使用Mocha对事件处理程序进行单元测试的正确方法是什么？

我有一个函数，它接受一个事件处理程序来处理接收到的消息，我想用Mocha为它编写一个单元测试

chat.setupBroadcastChannel = async (a, b, callback) => {
        // do something
        return await otherFunction(..)
    }
chat.sendBroadcastMessage= async (a, b) => {
        // do something
        return await sendMessage(..)
    }

我的测试如下所示：

it('should setup a broadcast channel and send and receive a broadcast message', () => {
        const testMessage = 'Hello!'
        let expectedMessage = '{d"sender":"self","message":"Hello!"}'
        let receivedMessage
        return chat.setupBroadcastChannel(broadcastTopic, false, (topic, partition, message) => {
                receivedMessage = message.value.toString()
                console.log('Test: Received a broadcast message', receivedMessage)
                console.log(receivedMessage, expectedMessage)
                assert.equal(receivedMessage, expectedMessage)
            })
            .then(async () => {
                await chat.sendBroadcastMessage('self', testMessage)
            })
    })

当

receivedMessage

与

expectedMessage

不匹配时，测试不起作用。看起来失败的断言是由Kafka（我正在使用的消息传递层）而不是Mocha接收的

{"level":"ERROR","timestamp":"2021-05-22T14:58:14.247Z","logger":"kafkajs","message":"[Runner] Error when calling
 eachMessage","topic":"broadcast","partition":0,"offset":"138","stack":"AssertionError [ERR_ASSERTION]:
 '{\"sender\":\"self\",\"message\":\"Hello!\"}' == '{d\"sender\":\"self\",\"message\":\"Hello!\"}'\n
 at D:\\path\\test\\chat.js:21:20\n    at Runner.eachMessage (D:\\path\\backend\\kafka.js:44:17)\n
 at Runner.processEachMessage (D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:151:20)\n 
 at onBatch (D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:287:20)\n 
 at D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:339:21\n  
 at invoke (D:\\path\\node_modules\\kafkajs\\src\\utils\\concurrency.js:38:5)\n 
 at push (D:\\path\\node_modules\\kafkajs\\src\\utils\\concurrency.js:51:7)\n 
 at D:\\path\\node_modules\\kafkajs\\src\\utils\\concurrency.js:60:53\n 
 at new Promise (<anonymous>)\n  
 at D:\\path\\node_modules\\kafkajs\\src\\utils\\concurrency.js:60:20\n 
 at D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:329:11\n 
 at Array.map (<anonymous>)\n
 at D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:328:17\n 
 at processTicksAndRejections (internal/process/task_queues.js:93:5)\n 
 at async Promise.all (index 0)\n  
 at async Runner.fetch (D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:354:5)\n 
 at async D:\\path\\node_modules\\kafkajs\\src\\consumer\\runner.js:383:9",
 "error":{"generatedMessage":true,"code":"ERR_ASSERTION",
 "actual":"{\"sender\":\"self\",\"message\":\"Hello!\"}",
 "expected":"{d\"sender\":\"self\",\"message\":\"Hello!\"}","operator":"=="}}

{“level”：“ERROR”，“timestamp”：“2021-05-22T14:58:14.247Z”，“logger”：“kafkajs”，“message”：“[Runner]调用时出错”
每个消息”，“主题”：“广播”，“分区”：0，“偏移量”：“138”，“堆栈”：“断言错误”[ERR_ASSERTION]：
“{\'sender\'：\'self\'，\'message\'：\'Hello！\'}'='{d\'sender\'：\'self\'，\'message\'：\'Hello！\'}'\n
在Runner.eachMessage的D:\\path\\test\\chat.js:21:20\n处（D:\\path\\backend\\kafka.js:44:17）\n
在Runner.processEachMessage（D:\\path\\node\u modules\\kafkajs\\src\\consumer\\Runner.js:151:20）处\n
在onBatch（D:\\path\\node\u modules\\kafkajs\\src\\consumer\\runner.js:287:20）\n
在D:\\path\\node\u modules\\kafkajs\\src\\consumer\\runner.js:339:21\n
在调用时（D:\\path\\node\u modules\\kafkajs\\src\\utils\\concurrency.js:38:5）\n
推送时（D:\\path\\node\u modules\\kafkajs\\src\\utils\\concurrency.js:51:7）\n
在D:\\path\\node\u modules\\kafkajs\\src\\utils\\concurrency.js:60:53\n
在新的承诺下（）\n
在D:\\path\\node\u modules\\kafkajs\\src\\utils\\concurrency.js:60:20\n
位于D:\\path\\node\u modules\\kafkajs\\src\\consumer\\runner.js:329:11\n
位于Array.map（）\n
在D:\\path\\node\u modules\\kafkajs\\src\\consumer\\runner.js:328:17\n
在处理和拒绝时（内部/process/task\u queues.js:93:5）\n
在async Promise.all（索引0）上\n
在async Runner.fetch（D:\\path\\node\u modules\\kafkajs\\src\\consumer\\Runner.js:354:5）\n
在异步D:\\path\\node\u modules\\kafkajs\\src\\consumer\\runner.js:383:9“，
“error”：{“generatedMessage”：true，“code”：“ERR_断言”，
“实际”：“{\”发送者\“：\”自我\“，\”消息\“：\”你好！\“}”，
“应为“{d\”发件人\“：\”自我\“，\”消息\“：\”你好！\“}”，“操作员”：“==”}”

设置此测试的正确方法是什么