feat(concat): removed deprecated concat operator

spec/Observable-spec.ts

@@ -2,7 +2,7 @@ import { expect } from 'chai';
 import * as sinon from 'sinon';
 import { TeardownLogic } from '../src/internal/types';
 import { Observable, config, Subscription, Subscriber, Operator, NEVER, Subject, of, throwError, EMPTY } from 'rxjs';
-import { map, multicast, refCount, filter, count, tap, combineLatestWith, concat, merge, race, zip, catchError, publish, publishLast, publishBehavior, share} from 'rxjs/operators';
+import { map, multicast, refCount, filter, count, tap, combineLatestWith, concatWith, merge, race, zip, catchError, publish, publishLast, publishBehavior, share} from 'rxjs/operators';
 import { TestScheduler } from 'rxjs/testing';
 import { observableMatcher } from './helpers/observableMatcher';
 
@@ -1077,13 +1077,13 @@ describe('Observable.lift', () => {
     });
   });
 
-  it('should compose through concat', () => {
+  it('should compose through concatWith', () => {
     rxTestScheduler.run(({ cold, expectObservable }) => {
       const e1 = cold(' --a--b-|');
       const e2 = cold(' --x---y--|');
       const expected = '--a--b---x---y--|';
 
-      const result = MyCustomObservable.from(e1).pipe(concat(e2, rxTestScheduler));
+      const result = MyCustomObservable.from(e1).pipe(concatWith(e2));
 
       expect(result instanceof MyCustomObservable).to.be.true;
 

spec/observables/fromEvent-spec.ts

@@ -1,7 +1,7 @@
 /** @prettier */
 import { expect } from 'chai';
 import { fromEvent, NEVER, timer } from 'rxjs';
-import { mapTo, take, concat } from 'rxjs/operators';
+import { mapTo, take, concatWith } from 'rxjs/operators';
 import { TestScheduler } from 'rxjs/testing';
 import { observableMatcher } from '../helpers/observableMatcher';
 
@@ -21,7 +21,7 @@ describe('fromEvent', () => {
 
       const target = {
         addEventListener: (eventType: any, listener: any) => {
-          timer(delay1, delay2).pipe(mapTo('ev'), take(2), concat(NEVER)).subscribe(listener);
+          timer(delay1, delay2).pipe(mapTo('ev'), take(2), concatWith(NEVER)).subscribe(listener);
         },
         removeEventListener: (): void => void 0,
         dispatchEvent: (): void => void 0,

spec/observables/fromEventPattern-spec.ts

@@ -3,7 +3,7 @@ import { expect } from 'chai';
 import * as sinon from 'sinon';
 
 import { fromEventPattern, noop, NEVER, timer } from 'rxjs';
-import { mapTo, take, concat } from 'rxjs/operators';
+import { mapTo, take, concatWith } from 'rxjs/operators';
 import { TestScheduler } from 'rxjs/testing';
 import { observableMatcher } from '../helpers/observableMatcher';
 
@@ -22,7 +22,7 @@ describe('fromEventPattern', () => {
       const expected = '  -----x-x---';
 
       function addHandler(h: any) {
-        timer(time1, time2, rxTestScheduler).pipe(mapTo('ev'), take(2), concat(NEVER)).subscribe(h);
+        timer(time1, time2, rxTestScheduler).pipe(mapTo('ev'), take(2), concatWith(NEVER)).subscribe(h);
       }
       const e1 = fromEventPattern(addHandler);
 

spec/observables/interval-spec.ts

@@ -2,7 +2,7 @@
 import { expect } from 'chai';
 import { NEVER, interval, asapScheduler, animationFrameScheduler, queueScheduler } from 'rxjs';
 import { TestScheduler } from 'rxjs/testing';
-import { take, concat } from 'rxjs/operators';
+import { take } from 'rxjs/operators';
 import * as sinon from 'sinon';
 import { observableMatcher } from '../helpers/observableMatcher';
 

spec/observables/timer-spec.ts

@@ -1,6 +1,6 @@
 import { timer, NEVER, merge } from 'rxjs';
 import { TestScheduler } from 'rxjs/testing';
-import { mergeMap, take, concat } from 'rxjs/operators';
+import { mergeMap, take, concatWith } from 'rxjs/operators';
 import { observableMatcher } from '../helpers/observableMatcher';
 
 /** @test {timer} */
@@ -15,7 +15,7 @@ describe('timer', () => {
     rxTest.run(({ expectObservable }) => {
       const e1 = timer(6, 2, rxTest).pipe(
         take(4), // make it actually finite, so it can be rendered
-        concat(NEVER) // but pretend it's infinite by not completing
+        concatWith(NEVER) // but pretend it's infinite by not completing
       );
       const expected = '------a-b-c-d-';
       const values = {