如何有效地测试 deferred always

Question

在 jQuery ajax（或获取）always part or even in bluebird promises finally 中编写代码测试时，如下所示：

function doStuff() {
    console.log('stuff done');
}

function someFunction() {
    return $.get('someurl').always(doStuff);
}

我总是发现自己为此编写 (QUnit) 测试，例如：

QUnit.test("doStuff will be called when someFunction succeeds", function (assert) {
    var deferred = $.Deferred();
    var backup = $.get;
    $.get = function () { return deferred; };

    var doStuffIsCalled = false;
    doStuff = function(){ doStuffIsCalled = true; };

    deferred.resolve({});
    return someFunction().then(function(){
        $.get = backup;
        assert.ok(doStuffIsCalled);
    });
});

QUnit.test("doStuff will be called when someFunction fails", function (assert) {
    var deferred = $.Deferred();
    var backup = $.get;
    $.get = function () { return deferred; };

    var doStuffIsCalled = false;
    doStuff = function(){ doStuffIsCalled = true; };

    deferred.reject(new Error('some error'));
    return someFunction().catch(function(){
        $.get = backup;
        assert.ok(doStuffIsCalled);
    });
});

这可行，但有些冗长。有没有更有效的方法，最好是在单个测试中，直接测试在延迟的始终部分调用的代码？

Answer 1

您可以使用 Sinon.js 模拟 jQuery ajax（或获取）以及一般的承诺。

一种方法可以是：

function someFunction() {
    return $.get('/mytest').always(doStuff);
}

function givenFncExecutesAndServerRespondsWith(reponseNumber, contentType, response) {
    server.respondWith("GET", "/mytest", [reponseNumber, contentType, response]);
    someFunction();
    server.respond();
}

module("Testing server responses", {
    setup: function () {
        server = sinon.sandbox.useFakeServer();
        doStuff = sinon.spy();
    },
    teardown: function () {
        server.restore();
    }
});

test("doStuff will be called when someFunction succeeds", function () {
    givenFncExecutesAndServerRespondsWith(200, '', '');
    ok(doStuff.called, "spy called once");
});

test("doStuff will be called when someFunction fails", function () {
    givenFncExecutesAndServerRespondsWith(500, '', '');
    ok(doStuff.called, "spy called once");
});

您可以在此 fiddle 中使用此代码。如果您使用 done 或 fail 而不是 always 来调用回调，则相应的测试将失败。

代码解释如下：

创建一个假服务器和一个将充当 always 回调的间谍。
根据我们正在测试的内容修改服务器响应的响应编号。

希望对您有所帮助。

如何有效地测试 deferred always

How to efficiently test deferred always

javascript

jquery

promise

qunit