add implementation for removeSystemIfExists

src/repositories/UnoptimizedInMemoryRepository.ts

@@ -148,28 +148,35 @@ export class UnoptimizedInMemoryRepository implements GetterSetterRepository {
     }
   }
 
-  removeSystemIfExists(systemId: string): Promise<ISystem | null> {
-    return Promise.resolve(null);
+  public async removeSystemIfExists(systemId: string): Promise<ISystem | null> {
+    const index = this.systems.findIndex((s) => s.id === systemId);
+    if (index > -1) {
+      const systemToReturn = this.systems[index];
+      this.systems.splice(index, 1);
+      return systemToReturn;
+    }
+
+    return null;
   }
 
-  removeRouteIfExists(routeId: string): Promise<IRoute | null> {
-    return Promise.resolve(null);
+  public async removeRouteIfExists(routeId: string): Promise<IRoute | null> {
+    return null;
   }
 
-  removeShuttleIfExists(shuttleId: string): Promise<IShuttle | null> {
-    return Promise.resolve(null);
+  public async removeShuttleIfExists(shuttleId: string): Promise<IShuttle | null> {
+    return null;
   }
 
-  removeStopIfExists(stopId: string): Promise<IStop | null> {
-    return Promise.resolve(null);
+  public async removeStopIfExists(stopId: string): Promise<IStop | null> {
+    return null;
   }
 
-  removeOrderedStopIfExists(stopId: string, routeId: string): Promise<IOrderedStop | null> {
-    return Promise.resolve(null);
+  public async removeOrderedStopIfExists(stopId: string, routeId: string): Promise<IOrderedStop | null> {
+    return null;
   }
 
-  removeEtaIfExists(shuttleId: string, stopId: string): Promise<IEta | null> {
-    return Promise.resolve(null);
+  public async removeEtaIfExists(shuttleId: string, stopId: string): Promise<IEta | null> {
+    return null;
   }
 
   public async clearSystemData() {