For example: 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. Spy call, Spy call - Sinon.JS. 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: The original method can be restored by calling object.method.restore(). However, you create a new Paper object with an Origami property in your test. I'm using sinon-chai so the syntax is valid, but both tests fail. Another approach to isolating dependencies is to initialize them in the constructor of the class. To prove the point: var sinon = require ('sinon'); exports. 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. 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) Instead of calling sinon.stub or sinon.spy, sandbox.stub and sandbox.spy are used instead. Standalone test spies, stubs and mocks for JavaScript. var spy = sinon. This post intends to show how to mock a class in JavaScript for the purpose of Unit Testing. spy (); myAsyncFunction (spy) ... Constructor functions and ES6 classes are also supported. Sinon spy() creates function. On Thursday, February 23, 2017 at 2:38:03 AM UTC+9, Christian Johansen wrote: Private properties are implementation details. In Sinon, a spy calls through the method it is spying on. I am trying to create a spy on a constructor, and see if it gets called -- below are my tests. 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. I suppose you could do the following instead: sinon.assert.match(actual, expectation); Uses sinon.match to test if … 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. ... it will automatically restore the sinon.spy(), created for publish property? 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. @fatso83 Sure, I've already read related issues prior to posting this one.. Utils API sinon.createStubInstance(constructor); Creates a new object with the given function as the protoype and stubs all implemented functions. As such, a spy is a good choice whenever the goal of a test is to verify something happened. Unless the method in question is documented here, it should not be considered part of the public API, and thus is subject to change. MyClass = function {this. Sinon.JS has a few utilities used internally in lib/sinon.js. After stub a es6 class, I want to mock the return value when instantiating it. I am pulling my hair out trying to figure out how to mock a constructor using sinon. 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. It does not spy on another function. require resolves paths before looking in its cache, so it should not matter that the paths are different. sinon.assert.alwaysThrew(spy, exception); Like above, only required for all calls to the spy. 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