javascript - Mocha 测试提示未处理的 Promise，但使用带有 catch block 的 async/await

Question

这些天我经常使用 async/await，但我有一个 Mocha 测试，我正在测试以确保确实抛出错误。下面您可以看到我必须捕获此错误的 try/catch block 。绿色和灰色方 block 是由 Wallaby(实时测试工具)插入的，表示从未到达 catch block 。

当我从命令行运行 mocha 时，我收到以下消息:

UnhandledPromiseRejectionWarning: FireModel::WrongRelationshipType: Can not use property "employer" on fancyperson with addToRelationship() because it is not a hasMany relationship [ relType: ownedBy, inverse: undefined ]. If you are working with a ownedBy relationship then you should instead use setRelationship() and clearRelationship().

addToRelationship() 的第一行检查关系类型是否正确(不正确)并抛出错误:

_errorIfNotHasManyReln 方法相当平淡，但为了完整起见，这里是:

protected _errorIfNotHasManyReln(
  property: Extract<keyof T, string>,
  fn: string
) {
  if (this.META.property(property).relType !== "hasMany") {
    const e = new Error(
      `Can not use property "${property}" on ${
        this.modelName
      } with ${fn}() because it is not a hasMany relationship [ relType: ${
        this.META.property(property).relType
      }, inverse: ${
        this.META.property(property).inverse
      } ]. If you are working with a ownedBy relationship then you should instead use setRelationship() and clearRelationship().`
    );
    e.name = "FireModel::WrongRelationshipType";
    throw e;
  }

有人可以帮我确定为什么这个错误没有被捕获吗？无奈之下，我在调用 _errorIfNotHasManyreln 的调用周围添加了另一个 try/catch block ，它确实捕获了错误，但随后我尝试重新抛出它，并再次陷入相同的情况。

Answer 1

您的 addToRelationship 方法也是异步的。您还必须等待 promise 响应:

try {
    await bob.addToRelationship("employer", "4567");
}
catch(e) {
    [...]
}

如果没有延迟到 promise 拒绝，则 try/catch 不会收到任何同步和终止的内容。然后发生了异常，显然没有被捕获。