Require ObservableScopes of state holders to be specified explicitly

Previously we had a ViewModel class which was responsible for little more than creating an ObservableScope. However, since this ObservableScope would be created implicitly upon view model construction, it became a tad bit harder for callers to remember to eventually end the scope (as you wouldn't just have to remember to end ObservableScopes, but also to destroy ViewModels). Requiring the scope to be specified explicitly by the caller also makes it possible for the caller to reuse the scope for other purposes, reducing the number of scopes mentally in flight that need tending to, and for all state holders (not just view models) to be handled uniformly by helper functions such as generateKeyed$.

src/utils/test.ts

@@ -6,7 +6,7 @@ Please see LICENSE in the repository root for full details.
 */
 import { map, type Observable, of, type SchedulerLike } from "rxjs";
 import { type RunHelpers, TestScheduler } from "rxjs/testing";
-import { expect, type MockedObject, vi, vitest } from "vitest";
+import { expect, type MockedObject, onTestFinished, vi, vitest } from "vitest";
 import {
   type RoomMember,
   type Room as MatrixRoom,
@@ -89,6 +89,15 @@ interface TestRunnerGlobal {
   rxjsTestScheduler?: SchedulerLike;
 }
 
+/**
+ * Create a new ObservableScope which ends when the current test ends.
+ */
+export function testScope(): ObservableScope {
+  const scope = new ObservableScope();
+  onTestFinished(() => scope.end());
+  return scope;
+}
+
 /**
  * Run Observables with a scheduler that virtualizes time, for testing purposes.
  */
@@ -267,6 +276,7 @@ export async function withLocalMedia(
   continuation: (vm: LocalUserMediaViewModel) => void | Promise<void>,
 ): Promise<void> {
   const vm = new LocalUserMediaViewModel(
+    testScope(),
     "local",
     mockMatrixRoomMember(localRtcMember, roomMember),
     constant(localParticipant),
@@ -280,11 +290,8 @@ export async function withLocalMedia(
     constant(null),
     constant(null),
   );
-  try {
-    await continuation(vm);
-  } finally {
-    vm.destroy();
-  }
+  // TODO: Simplify to just return the view model
+  await continuation(vm);
 }
 
 export function mockRemoteParticipant(
@@ -308,6 +315,7 @@ export async function withRemoteMedia(
 ): Promise<void> {
   const remoteParticipant = mockRemoteParticipant(participant);
   const vm = new RemoteUserMediaViewModel(
+    testScope(),
     "remote",
     mockMatrixRoomMember(localRtcMember, roomMember),
     of(remoteParticipant),
@@ -321,11 +329,8 @@ export async function withRemoteMedia(
     constant(null),
     constant(null),
   );
-  try {
-    await continuation(vm);
-  } finally {
-    vm.destroy();
-  }
+  // TODO: Simplify to just return the view model
+  await continuation(vm);
 }
 
 export function mockConfig(config: Partial<ResolvedConfigOptions> = {}): void {