Let's say i have 

```
import {ServerService} from './server-service'
import {ServerServiceMock} from './server-service-mock'

```

and

```
constructor (
    private serverService: ServerService
) {}

```

How would I switch programmatically lets say with a method, between both services? Needless to say there is lots of code depending on this.

Or maybe go into the services itself?

```
export class AuthZeroLockService {
    if buttonSwitch == true {
        return {//normalservice}
    } else {
        return {//mockedservice}
    }
}

```