feat: Add support for the Notification specification

test/unit/server/notifications/BaseStateHandler.test.ts

@@ -0,0 +1,50 @@
+import { BaseStateHandler } from '../../../../src/server/notifications/BaseStateHandler';
+import type { NotificationHandler } from '../../../../src/server/notifications/NotificationHandler';
+import type { SubscriptionInfo, SubscriptionStorage } from '../../../../src/server/notifications/SubscriptionStorage';
+
+describe('A BaseStateHandler', (): void => {
+  let info: SubscriptionInfo;
+  let notificationHandler: jest.Mocked<NotificationHandler>;
+  let storage: jest.Mocked<SubscriptionStorage>;
+  let handler: BaseStateHandler;
+
+  beforeEach(async(): Promise<void> => {
+    info = {
+      id: 'id',
+      topic: 'http://example.com/foo',
+      type: 'type',
+      features: {},
+      lastEmit: 0,
+      state: '123',
+    };
+
+    notificationHandler = {
+      handleSafe: jest.fn(),
+    } as any;
+
+    storage = {
+      update: jest.fn(),
+    } as any;
+
+    handler = new BaseStateHandler(notificationHandler, storage);
+  });
+
+  it('calls the handler if there is a trigger.', async(): Promise<void> => {
+    await expect(handler.handleSafe({ info })).resolves.toBeUndefined();
+    expect(notificationHandler.handleSafe).toHaveBeenCalledTimes(1);
+    // Note that jest stores a reference to the input object so we can't see that the state value was still there
+    expect(notificationHandler.handleSafe).toHaveBeenLastCalledWith({ topic: { path: info.topic }, info });
+    expect(info.state).toBeUndefined();
+    expect(storage.update).toHaveBeenCalledTimes(1);
+    expect(storage.update).toHaveBeenLastCalledWith(info);
+  });
+
+  it('does not delete the state parameter if something goes wrong.', async(): Promise<void> => {
+    notificationHandler.handleSafe.mockRejectedValue(new Error('bad input'));
+    await expect(handler.handleSafe({ info })).resolves.toBeUndefined();
+    expect(notificationHandler.handleSafe).toHaveBeenCalledTimes(1);
+    expect(notificationHandler.handleSafe).toHaveBeenLastCalledWith({ topic: { path: info.topic }, info });
+    expect(info.state).toBe('123');
+    expect(storage.update).toHaveBeenCalledTimes(0);
+  });
+});