Javascript 如何包装函数';结果是茉莉花
我有一个函数,我想处理它的输出。这有点像andCallThrough和andCallFake的组合。例如,假设我有一个构造函数:Javascript 如何包装函数';结果是茉莉花,javascript,mocking,jasmine,Javascript,Mocking,Jasmine,我有一个函数,我想处理它的输出。这有点像andCallThrough和andCallFake的组合。例如,假设我有一个构造函数: function Widget() { this.frobble = function() {return 1;}; } function frotz() { return new Widget().frobble(); } 我想做的是这样的事情: describe("Widget", function() { it("is created and f
function Widget() {
this.frobble = function() {return 1;};
}
function frotz() {
return new Widget().frobble();
}
我想做的是这样的事情:
describe("Widget", function() {
it("is created and frobbled when frotz() is called", function() {
var widget;
spyOn(window, 'Widget').andMessWithOutput(function(newWidget) {
widget = newWidget;
spyOn(widget, 'frobble').andCallThrough();
frotz();
expect(widget.frobble.calls.length).toBe(1);
});
});
});
我发现最好的方法是:
it("is clumsily created and frobbled when frotz() is called", function() {
var widget;
spyOn(window, 'Widget').andCallFake(function() {
// originalValue is the original spied-upon value. note that if it's a constructor
// you've got to call it with new (though that shouldn't seem unusual).
widget = new Widget.originalValue();
spyOn(widget, 'frobble').andCallThrough();
frotz();
expect(widget.frobble.calls.length).toBe(1);
});
});
我有一个助手,我用这个,也许它可以对其他人有用
// testUtils.js
module.exports = {
spyOn: customSpyOn
};
function customSpyOn(obj, name) {
const fn = obj[name];
return {
and: {
wrapWith: wrapWith
}
};
function wrapWith(wrapper) {
obj[name] = jasmine.createSpy(`wrapped: ${name}`)
.and.callFake(spyWrapper);
return obj[name];
function spyWrapper() {
const args = [].slice.call(arguments);
return wrapper.apply(obj, [fn].concat(args));
}
}
}
用法
如果你想增加间谍的回报价值
const connection = socket.createConnection('ws://whatever.com/live', {
format: 'json'
});
connection.open();
// etc...
您的规范和设置的顶部可能类似于
// some.spec.js
const testUtils = require('./testUtils');
testUtils.spyOn(socket, 'createConnection')
.and
.wrapWith(function(original, url, options) {
var api = original(url, options);
spyOn(api, 'open').and.callThrough();
spyOn(api, 'close').and.callThrough();
spyOn(api, 'send').and.callThrough();
return api;
});