Fix and add a test for toDevice ordering

spec/unit/webrtc/callEventHandler.spec.ts

@@ -0,0 +1,83 @@
+import { TestClient } from '../../TestClient';
+import { CallEventHandler } from '../../../src/webrtc/callEventHandler';
+import { MatrixEvent } from '../../../src/models/event';
+import { EventType } from '../../../src/@types/event';
+
+describe('CallEventHandler', function() {
+    let client;
+
+    beforeEach(function() {
+        client = new TestClient("@alice:foo", "somedevice", "token", undefined, {});
+    });
+
+    afterEach(function() {
+        client.stop();
+    });
+
+    it('should enforce inbound toDevice message ordering', async function() {
+        const callEventHandler = new CallEventHandler(client);
+
+        const event1 = new MatrixEvent({
+            type: EventType.CallInvite,
+            content: {
+                call_id: "123",
+                seq: 0,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event1);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(1);
+        expect(callEventHandler.callEventBuffer[0]).toBe(event1);
+
+        const event2 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 1,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event2);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(2);
+        expect(callEventHandler.callEventBuffer[1]).toBe(event2);
+
+        const event3 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 3,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event3);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(2);
+        expect(callEventHandler.nextSeqByCall.get("123")).toBe(2);
+        expect(callEventHandler.toDeviceEventBuffers.get("123").length).toBe(1);
+
+        const event4 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 4,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event4);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(2);
+        expect(callEventHandler.nextSeqByCall.get("123")).toBe(2);
+        expect(callEventHandler.toDeviceEventBuffers.get("123").length).toBe(2);
+
+        const event5 = new MatrixEvent({
+            type: EventType.CallCandidates,
+            content: {
+                call_id: "123",
+                seq: 2,
+            },
+        });
+        callEventHandler["onToDeviceEvent"](event5);
+
+        expect(callEventHandler.callEventBuffer.length).toBe(5);
+        expect(callEventHandler.nextSeqByCall.get("123")).toBe(5);
+        expect(callEventHandler.toDeviceEventBuffers.get("123").length).toBe(0);
+    });
+});