Jest createSpyObj

Question

With Chai, you can create a spy object as follows:

chai.spy.object([ \'push\', \'pop\' ]);

With jasmine, you can use:

jasmi         


        

Answer 1

David's answer helped to get me on the right track. I modified it to work with ionic-mocks (https://github.com/stonelasley/ionic-mocks) in my Ionic3/Angular4 project.

In my test "helper" class, I have this:

export function  createSpyObj (baseName: string, methodNames: string[]): { [key: string]: jasmine.Spy } {
  const obj: any = {}
  for (let i: number = 0; i < methodNames.length; i++) {
    obj[methodNames[i]] = jasmine.createSpy(baseName, () => {})
  }
  return obj
}

Then I'm able to use it as such in my test/spec file. I inject the provider in question as:

{ provide: AlertController, useFactory: () => AlertControllerMock.instance() },

And until ionic-mocks is compatible with Jest, I have to copy over the mocks I want (which use createSpyObj):

class AlertMock {
  public static instance (): any {
    const instance: any = createSpyObj('Alert', ['present', 'dismiss'])
    instance.present.and.returnValue(Promise.resolve())
    instance.dismiss.and.returnValue(Promise.resolve())

    return instance
  }
}

class AlertControllerMock {
  public static instance (alertMock?: AlertMock): any {

    const instance: any = createSpyObj('AlertController', ['create'])
    instance.create.and.returnValue(alertMock || AlertMock.instance())

    return instance
  }
}