No, interfaces are not supported for DI. With TypeScript interfaces are not available at runtime anymore, only statically and therefore can’t be used as DI tokens.
Alternatively you can use strings as keys or InjectionToken
provide('CoursesServiceInterface', {useClass: CoursesServiceMock}) // old
providers: [{provide: 'CoursesServiceInterface', useClass: CoursesServiceMock}]
and inject it like
constructor(@Inject('CoursesServiceInterface') private coursesService:CoursesServiceInterface) {}
See also https://angular.io/api/core/InjectionToken