add test case for null next stop

test/resolvers/OrderedStopResolverTests.test.ts

@@ -107,7 +107,26 @@ describe("OrderedStopResolvers", () => {
     });
 
     it("returns null if there is no next stop in the repository", async () => {
+      const orderedStops = await setUpOrderedStopsInRepository();
+      orderedStops[0].nextStop = undefined;
+      await repository.addOrUpdateOrderedStop(orderedStops[0]);
 
+      const response = await testServer.executeOperation({
+        query,
+        variables: {
+          systemId: mockSystem.id,
+          routeId: mockRoute.id,
+          stopId: orderedStops[0].stopId,
+        },
+      }, {
+        contextValue: {
+          repository,
+        }
+      });
+
+      assert(response.body.kind === "single");
+      const nonexistentNextStop = (response.body.singleResult.data?.system as any).route.orderedStop.nextStop;
+      expect(nonexistentNextStop).toBeNull();
     });
 
     it("returns null if the current stop no longer exists", async () => {

test/resolvers/ShuttleResolverTests.test.ts

@@ -7,6 +7,14 @@ import { IShuttle, ISystem } from "../../src/entities/entities";
 import assert = require("node:assert");
 import { setUpTestServer } from "../testHelpers/apolloSetupHelpers";
 
+async function addMockSystemToRepository(mockSystem: ISystem, repository: UnoptimizedInMemoryRepository) {
+  const mockSystems = generateMockSystems();
+  mockSystem = mockSystems[0];
+  mockSystem.id = "1";
+  await repository.addOrUpdateSystem(mockSystem);
+  return mockSystem;
+}
+
 describe("ShuttleResolvers", () => {
   let testServer: ApolloServer<ServerContext>
   let repository: UnoptimizedInMemoryRepository;
@@ -20,10 +28,7 @@ describe("ShuttleResolvers", () => {
   let mockShuttle: IShuttle;
 
   beforeEach(async () => {
-    const mockSystems = generateMockSystems();
-    mockSystem = mockSystems[0];
-    mockSystem.id = "1";
-    await repository.addOrUpdateSystem(mockSystem);
+    mockSystem = await addMockSystemToRepository(mockSystem, repository);
 
     const mockShuttles = generateMockShuttles();
     mockShuttle = mockShuttles[0];