Make screen sharing work more like speaking marbles in tests

This approach is more flexible in that it allows even the local participant to share their screen in CallViewModel tests, and more rigorous in that it ensures that application code is reacting specifically to track publications.

src/state/CallViewModel/CallViewModel.test.ts

@@ -105,15 +105,7 @@ const dave = mockMatrixRoomMember(daveRtcMember, { rawDisplayName: "Dave" });
 const daveId = `${dave.userId}:${daveRtcMember.deviceId}`;
 
 const localParticipant = mockLocalParticipant({ identity: "" });
-const aliceSharingScreen = mockRemoteParticipant({
-  identity: aliceId,
-  isScreenShareEnabled: true,
-});
 const bobParticipant = mockRemoteParticipant({ identity: bobId });
-const bobSharingScreen = mockRemoteParticipant({
-  identity: bobId,
-  isScreenShareEnabled: true,
-});
 const daveParticipant = mockRemoteParticipant({ identity: daveId });
 
 export interface GridLayoutSummary {
@@ -281,7 +273,8 @@ describe.each([
     withTestScheduler(({ behavior, schedule, expectObservable }) => {
       // Start with no screen shares, then have Alice and Bob share their screens,
       // then return to no screen shares, then have just Alice share for a bit
-      const participantInputMarbles = "    abcda-ba";
+      const aliceSharingInputMarbles = "   ny-n--yn";
+      const bobSharingInputMarbles = "     n-y-n---";
       // While there are no screen shares, switch to spotlight manually, and then
       // switch back to grid at the end
       const modeInputMarbles = "           -----s--g";
@@ -292,13 +285,12 @@ describe.each([
       const expectedShowSpeakingMarbles = "y----nyny";
       withCallViewModel(
         {
-          remoteParticipants$: behavior(participantInputMarbles, {
-            a: [aliceParticipant, bobParticipant],
-            b: [aliceSharingScreen, bobParticipant],
-            c: [aliceSharingScreen, bobSharingScreen],
-            d: [aliceParticipant, bobSharingScreen],
-          }),
+          remoteParticipants$: constant([aliceParticipant, bobParticipant]),
           rtcMembers$: constant([localRtcMember, aliceRtcMember, bobRtcMember]),
+          sharingScreen: new Map([
+            [aliceParticipant, behavior(aliceSharingInputMarbles, yesNo)],
+            [bobParticipant, behavior(bobSharingInputMarbles, yesNo)],
+          ]),
         },
         (vm) => {
           schedule(modeInputMarbles, {
@@ -688,7 +680,7 @@ describe.each([
       withCallViewModel(
         {
           remoteParticipants$: constant([
-            aliceSharingScreen,
+            aliceParticipant,
             bobParticipant,
             daveParticipant,
           ]),
@@ -702,6 +694,7 @@ describe.each([
             [bobParticipant, behavior(bSpeakingInputMarbles, yesNo)],
             [daveParticipant, behavior(dSpeakingInputMarbles, yesNo)],
           ]),
+          sharingScreen: new Map([[aliceParticipant, constant(true)]]),
         },
         (vm) => {
           schedule(modeInputMarbles, {
@@ -856,26 +849,30 @@ describe.each([
     withTestScheduler(({ behavior, expectObservable }) => {
       // iterate through a number of combinations of participants and MatrixRTC memberships
       // Bob never has an MatrixRTC membership
-      const scenarioInputMarbles = " abcdec";
+      const participantInputMarbles = "abcd-c";
+      // Bob even tries to share his screen at the end
+      const bobSharingInputMarbles = " n---yn";
       // Bob should never be visible
-      const expectedLayoutMarbles = "a-bc-b";
+      const expectedLayoutMarbles = "  a-bc-b";
 
       withCallViewModel(
         {
-          remoteParticipants$: behavior(scenarioInputMarbles, {
+          remoteParticipants$: behavior(participantInputMarbles, {
             a: [],
             b: [bobParticipant],
             c: [aliceParticipant, bobParticipant],
             d: [aliceParticipant, daveParticipant, bobParticipant],
-            e: [aliceParticipant, daveParticipant, bobSharingScreen],
           }),
-          rtcMembers$: behavior(scenarioInputMarbles, {
+          rtcMembers$: behavior(participantInputMarbles, {
             a: [localRtcMember],
             b: [localRtcMember],
             c: [localRtcMember, aliceRtcMember],
             d: [localRtcMember, aliceRtcMember, daveRtcMember],
             e: [localRtcMember, aliceRtcMember, daveRtcMember],
           }),
+          sharingScreen: new Map([
+            [bobParticipant, behavior(bobSharingInputMarbles, yesNo)],
+          ]),
         },
         (vm) => {
           vm.setGridMode("grid");

src/state/CallViewModel/CallViewModelTestUtils.ts

@@ -15,7 +15,7 @@ import {
   type Room as LivekitRoom,
 } from "livekit-client";
 import { SyncState } from "matrix-js-sdk/lib/sync";
-import { BehaviorSubject, type Observable, map, of } from "rxjs";
+import { BehaviorSubject, combineLatest, map, of } from "rxjs";
 import { onTestFinished, vi } from "vitest";
 import { ClientEvent, type RoomMember, type MatrixClient } from "matrix-js-sdk";
 import EventEmitter from "events";
@@ -68,7 +68,8 @@ export interface CallViewModelInputs {
   rtcMembers$: Behavior<Partial<CallMembership>[]>;
   roomMembers: RoomMember[];
   livekitConnectionState$: Behavior<ConnectionState>;
-  speaking: Map<Participant, Observable<boolean>>;
+  speaking: Map<Participant, Behavior<boolean>>;
+  sharingScreen: Map<Participant, Behavior<boolean>>;
   mediaDevices: MediaDevices;
   initialSyncState: SyncState;
   windowSize$: Behavior<{ width: number; height: number }>;
@@ -94,6 +95,7 @@ export function withCallViewModel(mode: MatrixRTCMode) {
         ConnectionState.Connected,
       ),
       speaking = new Map(),
+      sharingScreen = new Map(),
       mediaDevices = mockMediaDevices({}),
       initialSyncState = SyncState.Syncing,
       windowSize$ = constant({ width: 1000, height: 800 }),
@@ -154,13 +156,19 @@ export function withCallViewModel(mode: MatrixRTCMode) {
     const eventsSpy = vi
       .spyOn(ComponentsCore, "observeParticipantEvents")
       .mockImplementation((p, ...eventTypes) => {
-        if (eventTypes.includes(ParticipantEvent.IsSpeakingChanged)) {
-          return (speaking.get(p) ?? of(false)).pipe(
-            map((s): Participant => ({ ...p, isSpeaking: s }) as Participant),
-          );
-        } else {
-          return of(p);
-        }
+        return combineLatest([
+          (eventTypes.includes(ParticipantEvent.IsSpeakingChanged) &&
+            speaking.get(p)) ||
+            constant(false),
+          (eventTypes.includes(ParticipantEvent.TrackPublished) &&
+            sharingScreen.get(p)) ||
+            constant(false),
+        ]).pipe(
+          map(
+            ([isSpeaking, isScreenShareEnabled]) =>
+              ({ ...p, isSpeaking, isScreenShareEnabled }) as Participant,
+          ),
+        );
       });
 
     const roomEventSelectorSpy = vi