i am getting error "this.armService.getIsLoaded is not a function"

this.azureSubscriber = this.armService.getIsLoaded().takeWhile(() => this.alive).subscribe(isLoaded => {if(isLoaded) {this.spinner.stop();this.keyForm.get('tenant').enable();this.alive = false;}

"when i am testing i.e when i wrote spinner.stop toHaveBeencalled getting error "