Jasmine中返回Deferred的模拟嵌套函数

var module = function() {
  function getData(callback) {
    IP.read().done(function (data) {
        console.log("done");
        callback(data);
    });
  }
  return {
    getData: getData
  }
}();

var client = new $.RestClient('/rest/api/');
var IP = client.add('ip');

我看到了两种方法：

1. 监视$.ajax()并调用返回您自己的延迟的fake函数

   Contra：您间接测试库

2. 模拟$.RestClient的接口并返回您自己的延迟

   Contra：当不仅需要测试回调时，还要做更多的工作来模拟库。（你的嘲讽越复杂，你的测试就越容易出错。）

---

TL；DR如果已知，则跳过此项。

但首先让我们看看RestClient是如何工作的。。。它有两个基本对象，一个资源和一个动词。RestClient实际上是一个Resource对象（1）。当CCD_ 11返回一个休息片段（2）时，CCD_ 9对象将返回另一个CCD_。预定义的谓词read将返回Verb实例的call方法（3）。

1. https://github.com/jpillora/jquery.rest/blob/gh-pages/dist/jquery.rest.js#L382
2. https://github.com/jpillora/jquery.rest/blob/gh-pages/dist/jquery.rest.js#L241
3. https://github.com/jpillora/jquery.rest/blob/gh-pages/dist/jquery.rest.js#L245

从该链的底部到顶部，可以从call()方法（4）访问request方法。如果未明确重写，则默认为$.ajax()。（5）

4. https://github.com/jpillora/jquery.rest/blob/gh-pages/dist/jquery.rest.js#L174
5. https://github.com/jpillora/jquery.rest/blob/gh-pages/dist/jquery.rest.js#L66

如果没有不同的配置，对read()的调用将导致对$.ajax()的调用，并返回promise。

所以，当做新的new $.RestClient().add("...").add("...").read()时，你会得到$.ajax()的效果。

---

变体1:

describe("getData()", function(){
        // Handle to ajax()' deferred, scoped to the
        // describe so the fake ajax() and the it()
        // have access to it
    var def,
        underTest;
    beforeEach(function(){
        // Mock $.ajax (or what a Verb calls in the end)
        // assign "def" with a deferred and return it,
        // the test can then resolve() or reject() it
        spyOn($, "ajax").and.callFake(function(opts) {
            def = $.Deferred();
            return def;
        });
        // This is under test
        underTest = new UnderTest();
    });
    afterEach(function(){
        // Ensure a missing call of ajax() will fail the test
        def = null;
    });
    it("should call callback on successful read", function() {
        var callback = jasmine.createSpy("callback");
        // Indirectly call ajax() which will create def
        underTest.getData(callback);
        // Resolve the deferred to succeed the response
        def.resolve({a: 1});
        expect(callback).toHaveBeenCalledWith({a: 1});
    });
    it("should not call callback on failed read", function(){
        var callback = jasmine.createSpy("callback");
        underTest.getData(callback);
        def.reject();
        expect(callback).not.toHaveBeenCalled();
    });
});

假的是返回一个延迟的，而不是承诺，但在这种情况下，这是可以的，因为它有相同的接口，除了我们之外，任何人都不应该拒绝或解决延迟。

变体2:

describe("getData()", function(){
        // Store original reference
    var origRestClient,
        // See first code block
        def,
        underTest;
    // Mock thr Resouce object
    function MockResource() { }
    // Simplify the behaviour of this mock,
    // return another Mock resource
    MockResource.prototype.add = function() {
        return new MockResource();
    };
    // What Verb.call() would do, but directly
    // return a deferred
    MockResource.prototype.read = function() {
        def = $.Deferred();
        return def;
    };
    beforeEach(function(){
        // Replace RestClient
        origRestClient = $.RestClient;
        $.RestClient = MockResource;
        underTest = new UnderTest();
    });
    afterEach(function(){
        // Restore RestClient
        $.RestClient = origRestClient;
        def = null;
    });
    it("should call callback on successful read", function() {
        var callback = jasmine.createSpy("callback");
        underTest.getData(callback);
        def.resolve({a: 1});
        expect(callback).toHaveBeenCalledWith({a: 1});
    });
    it("should not call callback on failed read", function(){
        var callback = jasmine.createSpy("callback");
        underTest.getData(callback);
        def.reject();
        expect(callback).not.toHaveBeenCalled();
    });
});

如果您也想测试路径和请求数据，那么对Resouce的嘲讽需要比我所做的更多的工作，而使用上面的代码，这是不可能的。