Question

我创建了一个装饰器，它包含一个规则，当它被一个类多次使用时抛出，它的真正基本版本将如下所示：

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，如果开发人员尝试多次使用开发人员，则会抛出：

@someDecorator
@someDecorator // throws
class Test {

}

我希望编写单元测试以验证此功能，一切正常。我使用的是mocha，chai和sinon。

我如何断言someDecorator会抛出？

Answer 1

我如何断言someDecorator会抛出？

您基本上想要两次（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);
  });
});

断言装饰者抛出

2 个答案: