How to verify that a constructor was called using sinon

Question

I need to assert whether a constructor was called using sinon. Below is how I can create a spy.

let nodeStub: any;
nodeStub = this.createStubInstance("node");

But how can I verify that this constructor was called with the relevant parameters? Below is how the constructor is actually called.

 node = new node("test",2);

Any help would be much appreciated.

Below is the code I have.

import {Node} from 'node-sdk-js-browser';

export class MessageBroker {

    private node: Node;
    constructor(url: string, connectionParams: IConnectionParams) {
        this.node = new Node(url, this.mqttOptions, this.messageReceivedCallBack);
    }
}

Answer 1

Given the following code myClient.js:

const Foo = require('Foo');

module.exports = {
   doIt: () => {
      const f = new Foo("bar");
      f.doSomething();
  }
}

You can write a test like this:

const sandbox = sinon.sandbox.create();
const fooStub = {
   doSomething: sandbox.spy(),
}

const constructorStub = sandbox.stub().returns(fooStub);
const FooInitializer = sandbox.stub({}, 'constructor').callsFake(constructorStub);

// I use proxyquire to mock dependencies. Substitute in whatever you use here.
const client2 = proxyquire('./myClient', {
    'Foo': FooInitializer,
});

client2.doIt();

assert(constructorStub.calledWith("bar"));
assert(fooStub.doSomething.called);