类型“”中的属性“method”不可赋值给基类型中的同一属性

我们用可选实现了一个泛型类型,它使用默认类型,否则在运行方法时应该使用类型集。

type Test = {
  a: number;
  b: string;
}
interface IApple {
  // we can call it as `method()` fallbacks to `Test` type or with custom type like `method<AnotherType>()`
  method<T=Test>(): Promise<T> 
}

现在,当我写这样一节课的时候。

class Apple implements IApple {
   method() {
    return Promise.resolve({
        a: 10, 
        b: 'test',
     } as Test)
}

获取类型错误

Property 'method' in type 'Apple' is not assignable to the same property in base type 'IApple'.
  Type '() => Promise<{ a: number; b: string; }>' is not assignable to type '<T = Test>() => Promise<T>'.
    Type 'Promise<{ a: number; b: string; }>' is not assignable to type 'Promise<T>'.
      Type '{ a: number; b: string; }' is not assignable to type 'T'.
        'T' could be instantiated with an arbitrary type which could be unrelated to '{ a: number; b: string; }'.