prettier import { expect } from 'chai' ; import { dateTimestampProvider } from 'rxjs/internal/scheduler/dateTimestampProvider' ; describe ( 'dateTimestampProvider' , ( ) => { const originalDate = global . Date ; afterEach ( ( ) => { global . Date = originalDate ; } ) ; it ( 'should be monkey patchable' , ( ) => { let nowCalled = false ; global . Date = { now ( ) { nowCalled = true ; return 0 ; } , } as any ; dateTimestampProvider . now ( ) ; expect ( nowCalled ) . to . be . true ; } ) ; } ) ;