我有这个功能：

reload() {
    myService.queryData()
        .done(...)
        .always(() => throw "fake exception"); //just to simulate the failure
}

我想要我的测试重载函数,并确保它不会引发异常,也不会在promise回调中引发异常.

describe("reload", function () {
    it("does not throw exception", function (done) {

        spyOn(myService, "queryData").and.callFake(() => {
            let deffered = $.deffered();
            setTimeOut(() => deffered.reject(), 0)
            return deffered.promise();
        });

        reload();
        setTimeout(() => {
           //this is evaluated after the exception has been thrown, but
           //how to check whether exception has been thrown
        }, 2);
    });
});

编辑：在某些情况下,如果已经定义了函数的返回类型,例如组件的生命周期事件,我可能无法返回诺言：

MyComponent extends React.Component {
    componentDidMount() {
        this.load(
            galleryService.nodes().then(galleryResult => this.setState({ nodes: galleryResult.nodes }))
        );
        this.load(
            galleryService.caches().then(cachesResult => this.setState({ caches: cachesResult.caches }))
        );
    }
}

var myComponent = React.createElement(MyComponent);
TestUtils.renderIntoDocument(myComponent); //this triggers the componentDidMount event and I need to make sure it won't throw error.

解决方法:

让reload返回它创建的承诺.在您的测试用例中,在其上附加一个catch处理程序,这会触发测试失败：

reload().catch(err => done.fail(err));

编辑问题后进行更新：如果无法更改原始函数的返回值,则将相关部分分解为单独的函数.例如：

function reloadNodes() {
    return somePromise();
}

function reloadCaches() {
    return anotherPromise();
}

function reload() {
    reloadNodes();
    reloadCaches();
}

然后,您可以测试reloadNodes和reloadCaches而不是重新加载.显然,您不需要为每个promise创建单独的函数,而是在适当的地方使用诸如Promise.all之类的组合promise.