断言装饰器抛出

Question

我创建了一个装饰器，它包含一个规则，当它与 class 一起使用时抛出一个规则，它的一个真正的基本版本如下所示：

function someDecorator(target: any) {
    var msg = "Decorator can only be applyed once";
    if(target.annotated != undefined) throw new Error(msg);
    target.annotated = true;
}

因此，如果开发人员多次尝试使用该开发人员，它将抛出：

@someDecorator
@someDecorator // throws
class Test {

}

一切都按预期工作，我想编写一个单元测试来验证此功能。我正在使用 mocha、chai 和 sinon。

如何断言 someDecorator 抛出异常？

Answer 1

How can I assert that someDecorator throws?

你基本上想调用它两次 (someDecorator(someDecorator(function(){})) 和 assert a throw.

Answer 2

另一种可能的方法：

declare function __decorate(decorators, target, key?, desc?);
declare function __param(paramIndex, decorator);

describe("@named decorator \n", () => {
  it("It should throw when applayed mutiple times \n", () => {

    var useDecoratorMoreThanOnce = function() {
      __decorate([
          __param(0, named("a")),
          __param(0, named("b"))
      ], NamedTooManyTimesWarrior);
    };

    var msg = "Metadadata key named was used more than once in a parameter.";
    expect(useDecoratorMoreThanOnce).to.throw(msg);
  });
});

断言装饰器抛出

Assert decorator throws

decorator

mocha.js

sinon

chai

typescript