prettier import { observeOn , mergeMap , take } from 'rxjs/operators' ; import { TestScheduler } from 'rxjs/testing' ; import { expect } from 'chai' ; import { of , Observable , queueScheduler } from 'rxjs' ; import { observableMatcher } from '../helpers/observableMatcher' ; test describe ( 'observeOn' , ( ) => { let testScheduler ; beforeEach ( ( ) => { testScheduler = new TestScheduler ( observableMatcher ) ; } ) ; it ( 'should observe on specified scheduler' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --a--b--|' ) ; const e1subs = '  ^-------!' ; const expected = '--a--b--|' ; expectObservable ( e1 . pipe ( observeOn ( testScheduler ) ) ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should observe after specified delay' , ( ) => { testScheduler . run ( ( { hot , time , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '    --a----b-|   ' ) ; const e1subs = '    ^--------!   ' ; const delay = time ( '  ---|       ' ) ; const expected = '  -----a----b-|' ; expectObservable ( e1 . pipe ( observeOn ( testScheduler , delay ) ) ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should observe when source raises error' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --a--#' ) ; const e1subs = '  ^----!' ; const expected = '--a--#' ; expectObservable ( e1 . pipe ( observeOn ( testScheduler ) ) ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should observe when source is empty' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  -----|' ) ; const e1subs = '  ^----!' ; const expected = '-----|' ; expectObservable ( e1 . pipe ( observeOn ( testScheduler ) ) ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should observe when source does not complete' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  -----' ) ; const e1subs = '  ^----' ; const expected = '-----' ; expectObservable ( e1 . pipe ( observeOn ( testScheduler ) ) ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should allow unsubscribing early and explicitly' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --a--b--|' ) ; const e1subs = '  ^---!    ' ; const expected = '--a--    ' ; const unsub = '   ----!    ' ; const result = e1 . pipe ( observeOn ( testScheduler ) ) ; expectObservable ( result , unsub ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should not break unsubscription chains when the result is unsubscribed explicitly' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --a--b--|' ) ; const e1subs = '  ^---!    ' ; const expected = '--a--    ' ; const unsub = '   ----!    ' ; const result = e1 . pipe ( mergeMap ( ( x ) => of ( x ) ) , observeOn ( testScheduler ) , mergeMap ( ( x ) => of ( x ) ) ) ; expectObservable ( result , unsub ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should stop listening to a synchronous observable when unsubscribed' , ( ) => { const sideEffects = [ ] ; const synchronousObservable = new Observable < number > ( ( subscriber ) => { for ( let i = 0 ; ! subscriber . closed && i < 10 ; i ++ ) { sideEffects . push ( i ) ; subscriber . next ( i ) ; } } ) ; synchronousObservable . pipe ( observeOn ( queueScheduler ) , take ( 3 ) ) . subscribe ( ( ) => { } ) ; expect ( sideEffects ) . to . deep . equal ( [ 0 , 1 , 2 ] ) ; } ) ; } ) ;