Unit testing for ionic-angular Events Subscribe call

I am trying to write unit test case for Events.Subscribe method.
The events is published from a file A, with events.publish method as…
public showSuccessBannerPopup() {
this.events.publish(‘showMessage’, true);

And the event subscribed from the constructor of File B as…
public events: Events
) {
events.subscribe(‘showBannerMessage’, (showMessageStatus) => {
console.log(‘show Message called…’)
this.showMessage = showMessageStatus;

I am not able to write the unit test case in Jasmine for events.subscribe.

Could anybody help…

Even i have a similar situation , help us with solution