prettier import { expect } from 'chai' ; import { animationFrameProvider } from 'rxjs/internal/scheduler/animationFrameProvider' ; describe ( 'animationFrameProvider' , ( ) => { const originalRequest = global . requestAnimationFrame ; const originalCancel = global . cancelAnimationFrame ; afterEach ( ( ) => { global . requestAnimationFrame = originalRequest ; global . cancelAnimationFrame = originalCancel ; } ) ; it ( 'should be monkey patchable' , ( ) => { let requestCalled = false ; let cancelCalled = false ; global . requestAnimationFrame = ( ) => { requestCalled = true ; return 0 ; } ; global . cancelAnimationFrame = ( ) => { cancelCalled = true ; } ; const handle = animationFrameProvider . requestAnimationFrame ( ( ) => { } ) ; animationFrameProvider . cancelAnimationFrame ( handle ) ; expect ( requestCalled ) . to . be . true ; expect ( cancelCalled ) . to . be . true ; } ) ; } ) ;