Use the initialValue parameter of 'behavior' instead of startWith

src/state/CallViewModel.ts

@@ -403,7 +403,7 @@ export class CallViewModel extends ViewModel {
    */
   private readonly rawRemoteParticipants$ = this.scope.behavior<
     RemoteParticipant[]
-  >(connectedParticipantsObserver(this.livekitRoom).pipe(startWith([])));
+  >(connectedParticipantsObserver(this.livekitRoom), []);
 
   /**
    * Lists of RemoteParticipants to "hold" on display, even if LiveKit claims that
@@ -889,9 +889,7 @@ export class CallViewModel extends ViewModel {
       distinctUntilChanged(),
     );
 
-  private readonly pipEnabled$: Observable<boolean> = setPipEnabled$.pipe(
+  private readonly pipEnabled$ = this.scope.behavior(setPipEnabled$, false);
-    startWith(false),
-  );
 
   private readonly naturalWindowMode$ = this.scope.behavior<WindowMode>(
     fromEvent(window, "resize").pipe(

src/state/MediaDevices.ts

@@ -122,8 +122,8 @@ function availableRawDevices$(
             )
           : devices$,
       ),
-      startWith([]),
     ),
+    [],
   );
 }
 
@@ -373,10 +373,8 @@ export class MediaDevices {
   // API. This flag never resets to false, because once permissions are granted
   // the first time, the user won't be prompted again until reload of the page.
   private readonly usingNames$ = this.scope.behavior(
-    this.deviceNamesRequest$.pipe(
+    this.deviceNamesRequest$.pipe(map(() => true)),
-      map(() => true),
+    false,
-      startWith(false),
-    ),
   );
   public readonly audioInput: MediaDevice<
     DeviceLabel,

src/utils/test.ts

@@ -4,7 +4,7 @@ Copyright 2023, 2024 New Vector Ltd.
 SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
-import { map, type Observable, of, type SchedulerLike, startWith } from "rxjs";
+import { map, type Observable, of, type SchedulerLike } from "rxjs";
 import { type RunHelpers, TestScheduler } from "rxjs/testing";
 import { expect, vi, vitest } from "vitest";
 import {
@@ -125,9 +125,12 @@ export function withTestScheduler(
           values === undefined ? (initialMarble as T) : values[initialMarble];
         // The remainder of the marble diagram should start on frame 1
         return scope.behavior(
-          helpers
+          helpers.hot(
-            .hot(`-${marbles.slice(initialMarbleIndex + 1)}`, values, error)
+            `-${marbles.slice(initialMarbleIndex + 1)}`,
-            .pipe(startWith(initialValue)),
+            values,
+            error,
+          ),
+          initialValue,
         );
       },
     }),