prettier import { expect } from 'chai' ; import { startWith , mergeMap , take } from 'rxjs/operators' ; import { TestScheduler } from 'rxjs/testing' ; import { of , Observable } from 'rxjs' ; import { observableMatcher } from '../helpers/observableMatcher' ; test describe ( 'startWith' , ( ) => { const defaultStartValue = 'x' ; let testScheduler ; beforeEach ( ( ) => { testScheduler = new TestScheduler ( observableMatcher ) ; } ) ; it ( 'should prepend to a cold Observable' , ( ) => { testScheduler . run ( ( { cold , expectObservable , expectSubscriptions } ) => { const e1 = cold ( ' ---a--b--c--|' ) ; const e1subs = '  ^-----------!' ; const expected = 's--a--b--c--|' ; const result = e1 . pipe ( startWith ( 's' ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start an observable with given value' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --a--|' ) ; const e1subs = '  ^----!' ; const expected = 'x-a--|' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and does not completes if source does not completes' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  ----a-' ) ; const e1subs = '  ^-----' ; const expected = 'x---a-' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and does not completes if source never emits' , ( ) => { testScheduler . run ( ( { cold , expectObservable , expectSubscriptions } ) => { const e1 = cold ( ' - ' ) ; const e1subs = '  ^ ' ; const expected = 'x-' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and completes if source does not emits' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  ---|' ) ; const e1subs = '  ^--!' ; const expected = 'x--|' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and complete immediately if source is empty' , ( ) => { testScheduler . run ( ( { cold , expectObservable , expectSubscriptions } ) => { const e1 = cold ( ' |   ' ) ; const e1subs = '  (^!)' ; const expected = '(x|)' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and source both if source emits single value' , ( ) => { testScheduler . run ( ( { cold , expectObservable , expectSubscriptions } ) => { const e1 = cold ( ' (a|)' ) ; const e1subs = '  (^!)' ; const expected = '(xa|)' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given values when given value is more than one' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  -----a--|' ) ; const e1subs = '  ^-------!' ; const expected = '(yz)-a--|' ; const result = e1 . pipe ( startWith ( 'y' , 'z' ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and raises error if source raises error' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --#' ) ; const e1subs = '  ^-!' ; const expected = 'x-#' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected , defaultStartValue ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with given value and raises error immediately if source throws error' , ( ) => { testScheduler . run ( ( { cold , expectObservable , expectSubscriptions } ) => { const e1 = cold ( ' #   ' ) ; const e1subs = '  (^!)' ; const expected = '(x#)' ; const result = e1 . pipe ( startWith ( defaultStartValue ) ) ; expectObservable ( result ) . toBe ( expected , defaultStartValue ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should allow unsubscribing explicitly and early' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  ---a--b----c--d--|' ) ; const unsub = '   ---------!        ' ; const e1subs = '  ^--------!        ' ; const expected = 's--a--b---        ' ; const values = { s : 's' , a : 'a' , b : 'b' } ; const result = e1 . pipe ( startWith ( 's' , testScheduler ) ) ; expectObservable ( result , unsub ) . toBe ( expected , values ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should not break unsubscription chains when result is unsubscribed explicitly' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  ---a--b----c--d--|' ) ; const e1subs = '  ^--------!        ' ; const expected = 's--a--b---        ' ; const unsub = '   ---------!        ' ; const values = { s : 's' , a : 'a' , b : 'b' } ; const result = e1 . pipe ( mergeMap ( ( x ) => of ( x ) ) , startWith ( 's' , testScheduler ) , mergeMap ( ( x ) => of ( x ) ) ) ; expectObservable ( result , unsub ) . toBe ( expected , values ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should start with empty if given value is not specified' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  -a-|' ) ; const e1subs = '  ^--!' ; const expected = '-a-|' ; const result = e1 . pipe ( startWith ( testScheduler ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should accept scheduler as last argument with single value' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  --a--|' ) ; const e1subs = '  ^----!' ; const expected = 'x-a--|' ; const result = e1 . pipe ( startWith ( defaultStartValue , testScheduler ) ) ; expectObservable ( result ) . toBe ( expected ) ; expectSubscriptions ( e1 . subscriptions ) . toBe ( e1subs ) ; } ) ; } ) ; it ( 'should accept scheduler as last argument with multiple value' , ( ) => { testScheduler . run ( ( { hot , expectObservable , expectSubscriptions } ) => { const e1 = hot ( '  -----a--|' ) ; const e1subs = '  ^-------!' ; const expected = '(yz)-a--|' ; const result = e1 . pipe ( startWith ( 'y' , 'z' , testScheduler ) ) ; expectObservable ( result ) . 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 ( startWith ( - 1 ) , take ( 4 ) ) . subscribe ( ( ) => { } ) ; expect ( sideEffects ) . to . deep . equal ( [ 0 , 1 , 2 ] ) ; } ) ; } ) ;