add tests and implementation for notification deletes

src/repositories/InMemoryNotificationRepository.ts

@@ -19,7 +19,7 @@ export class InMemoryNotificationRepository implements NotificationRepository {
    */
   private deviceIdsToDeliverTo: { [key: string]: DeviceIdSecondsThresholdAssociation } = {}
 
-  private subscribers: Listener[] = [];
+  private listeners: Listener[] = [];
 
   async getAllNotificationsForShuttleAndStopId(shuttleId: string, stopId: string) {
     const tuple = new TupleKey(shuttleId, stopId);
@@ -81,12 +81,34 @@ export class InMemoryNotificationRepository implements NotificationRepository {
       return;
     }
 
+    const secondsThreshold = this.deviceIdsToDeliverTo[tupleKey.toString()][deviceId];
     delete this.deviceIdsToDeliverTo[tupleKey.toString()][deviceId];
+    this.listeners.forEach((listener) => {
+      const event: NotificationEvent = {
+        event: 'delete',
+        notification: {
+          deviceId,
+          shuttleId,
+          stopId,
+          secondsThreshold
+        }
+      }
+
+      listener(event);
+    })
   }
 
   public subscribeToNotificationChanges(listener: Listener): void {
+    const index = this.listeners.findIndex((existingListener) => existingListener == listener);
+    if (index < 0) {
+      this.listeners.push(listener);
+    }
   }
 
   public unsubscribeFromNotificationChanges(listener: Listener): void {
+    const index = this.listeners.findIndex((existingListener) => existingListener == listener);
+    if (index >= 0) {
+      this.listeners.splice(index, 1);
+    }
   }
 }