Mocking Constructors

[kanben-a]

Hi!

I'm just a TypeScript beginner, so I may not not have a full grasp on the thing I'm trying to do:

I'm currently trying to mock a constructor of an imported class- is there any way? Currently your library only allows to mock away functions.

class Test{
   constructor(hi:string){
       //how can i make sure this is called with the correct string
   }
}

EDIT:
TypeScript now compiles but throws the following error:

TypeError: Cannot stub non-existent own property default
      at Sandbox.stub (node_modules/sinon/lib/sinon/sandbox.js:308:19)
      at Function.ImportMock.mockFunction (node_modules/ts-mock-imports/src/import-mock.ts:18:18)

This is my test code:

      var queue_stub = ImportMock.mockFunction(queue);
      queue_stub.callsFake(function(queue_name, { redis }) {
        expect(queue_name).to.be.a("string");
        expect(redis).to.equal(mock_redis_config);
        return mock_queue;
      });

(I'm trying to mock Bull)

[EmandM]

What does the import of your test look like?

That error is thrown when your code is importing the library as import { Queue } from 'queue' which would mean you need to call ImportMock.mockFunction(queue, 'Queue') as ImportMock needs to know which export to replace.

[kanben-a]

Thanks for your repsonse!

My import looks like this:
import * as Queue from bull
this is needed because the bull package exposes the namespace and its constructor under the same name:

declare const Bull: {
  /* tslint:disable:no-unnecessary-generics unified-signatures */
  <T = any>(queueName: string, opts?: Bull.QueueOptions): Bull.Queue<T>;
  <T = any>(queueName: string, url: string, opts?: Bull.QueueOptions): Bull.Queue<T>;
  new <T = any>(queueName: string, opts?: Bull.QueueOptions): Bull.Queue<T>;
  new <T = any>(queueName: string, url: string, opts?: Bull.QueueOptions): Bull.Queue<T>;
  /* tslint:enable:no-unnecessary-generics unified-signatures */
};

declare namespace Bull {
  interface RateLimiter {
...

from: @types/bull

[l-ko]

not sure if it helps:

import * as someModule from 'some-module';

class Mocked extends someModule.default {
  constructor(args) {
    super(args);
    // Spectate args
  }
}
const mockManager = ImportMock.mockOther(someModule, 'default', Mocked);

[kanben-a]

Hmm, this is definitely a good way to start out and helps me to monitor stuff.
Thanks for your help!