In Sinon, a spy calls through the method it is spying on. Standalone test spies, stubs and mocks for JavaScript. spy (exports, 'MyClass'); var MyClass = exports. However, you create a new Paper object with an Origami property in your test. // Check that spy was called with `new` operator and uses constructor calledWithNew // Check that spy threw an exception at least once threw threw ("string") threw ... Sinon Spy Archi - Wrap old fn with new fn and use new fn in place of old one WITHOUT SPY - MyFn —-> Orig Fn; Instead of calling sinon.stub or sinon.spy, sandbox.stub and sandbox.spy are used instead. Thanks a bunch @fatso83 for that explanation, it really helped. Hence, when you spy on Paper, 'Origami', it is the property Origami of the Paper object you created locally in your test file which is replaced with a spy. I have a function that will create multiple widgets by calling a constructor that accepts a few arguments. Hi, I wonder if I'm using sinon (v3.1.0) correctly, trying to stub constructors and if we can make this task simpler. and.returnValue() A spy can be made to return a preset/fixed value (without the need for calling the actual methods using and.callThrough()). After stub a es6 class, I want to mock the return value when instantiating it. The original method can be restored by calling object.method.restore(). To prove the point: var sinon = require ('sinon'); exports. But I could not understand where I should use sinon.spy() to check whether this function has called or not. sinon.assert.alwaysThrew(spy, exception); Like above, only required for all calls to the spy. To solve this problem you can move the method myFunc in the prototype of the MyClass object and then spy the methods in the prototype. Another approach to isolating dependencies is to initialize them in the constructor of the class. In Chrome it fails with Uncaught TypeError: Failed to construct 'WebSocket': Please use the 'new' operator, this DOM object constructor cannot be called as a function. It does not spy on another function. Creates a spy for object.method and replaces the original method with the spy. It’s possible to assert on a dedicated spy call: sinon.assert.threw(spy.thirdCall, exception);. So, sinon.spy(s,'nextSeason'); in Sinon is equivalent to spyOn(s,'nextSeason').and.callThrough(); in Jasmine. Something like this: const spy = sinon.stub(InternalService.prototype, 'getEvents').returns([{ id: 1 }]); const internalService = new InternalService(); console.log(internalService.getEvents()); // => [{ id: 1 }] Since sinon.createStubInstance has been removed from latest versions of Sinon, I would suggest stubbing individual instance methods on the prototype, to achieve the desired effect. Any kind of help wou this answer edited Aug 15 '14 at 20:43 Aurélien Gasser ♦ 1,033 8 17 answered Jan 28 '13 at 21:12 ppoliani 2,299 1 15 47 Thanks ppoliani. The spy acts exactly like the original method in all cases. The function sinon.spy returns a Spy object, which can be called like a function, but also contains properties with information on any calls made to it. I suppose you could do the following instead: var c = new MyClass() var spy = sinon.spy(c, "myFunc"); Clearly the spy is not in place when the constructor is called. As such, a spy is a good choice whenever the goal of a test is to verify something happened. MyClass = function {this. Spy call, Spy call - Sinon.JS. spy (); myAsyncFunction (spy) ... Constructor functions and ES6 classes are also supported. When deciding if a test was successful based on the state of available objects alone is not sufficient, we can use test spies and make assertions on things such as the number of calls, arguments passed to specific functions, return values and more. Test constructor calling a method with Sinon I'd like to ensure that the constructor is calling a method when instantiated with Sinon, however, I can't seem to get this to work, as I believe the sinon is not watching the correct instantiation: A stub is a spy with predetermined behavior.. We can use a stub to: Take a predetermined action, like throwing an exception; Provide a predetermined response; Prevent a specific method from being called directly (especially when it triggers undesired behaviors like HTTP requests) On Thursday, February 23, 2017 at 2:38:03 AM UTC+9, Christian Johansen wrote: Private properties are implementation details. Sinon.JS has a few utilities used internally in lib/sinon.js. @fatso83 Sure, I've already read related issues prior to posting this one.. OP wants to SPY ON the standalone function. Let's say I have the following module: // moduleA.js const Thing = … In Safari or PhantomJs it fails with TypeError: Attempted to wrap object property WebSocket as function spy === object.method. How to properly mock ES6 classes with sinon, Sinon allows you to easily stub individual instance methods of objects. Sinon mock javascript class. Both proxyquire and rewire require … Utils API sinon.createStubInstance(constructor); Creates a new object with the given function as the protoype and stubs all implemented functions. It sounds like what I'd like to do is impossible, but for reasons that have nothing to do with ES6. javascript - method - sinon spy constructor . I'm using sinon-chai so the syntax is valid, but both tests fail. require resolves paths before looking in its cache, so it should not matter that the paths are different. A test spy is an object that records its interaction with other objects throughout the code base. Sinon spy() creates function. Combined with Sinon’s assertions, we can check many different results by using a simple spy. Of course b.js. Spying on a constructor using Jasmine (4) flipCounter is just another function, even if it also happens to construct an object. Stub. ... it will automatically restore the sinon.spy(), created for publish property? When doing so, the original function will behave just as normal (including when used as a constructor) but you will have access to data about all calls. Works with any unit testing framework. var spy = sinon. var foo = function(arg) { }; var Spying on a constructor in javascript with sinon (2) Considering your constructor is bound to 'window' which means that if you open developer console on your browser, you should be able to intantiate an object by using the related function/constructor as such: I want to verify that the constructor is called the correct number of times with the correct parameters, but I don't want to actually construct the widgets. The post targets developers who are coming to ES6 from … Spy call. sinon.assert.match(actual, expectation); Uses sinon.match to test if … I have changed my code to inject the dependency into the constructor. Unless the method in question is documented here, it should not be considered part of the public API, and thus is subject to change. This discrepancy occurs because Sinon wraps exports.MyClass with its own mechanism, which means that the MyClass local variable which points directly to the constructor remains unaffected. The thing that differs ES6 classes from ES5 constructor functions is a safeguard that prevents them from being used like var bar = Object.create(Bar.prototype); Bar.call(bar).. For example, a spy can tell us how many times a function was called, what arguments each call had, what values were returned, what errors were thrown, etc. What I'm trying to … This post intends to show how to mock a class in JavaScript for the purpose of Unit Testing. The returned spy is the function object which replaced the original method. class B { constructor() {} doOther(number) { return new var mock = sinon.mock(obj); Creates a mock for the provided object. 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