Add a functional 'mockServices.events()'

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

.changeset/pretty-corners-speak.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-test-utils': minor
+---
+
+Add a functional `mockServices.events()`

packages/backend-test-utils/report.api.md

@@ -222,14 +222,17 @@ export namespace mockServices {
         partialImpl?: Partial<DiscoveryService> | undefined,
       ) => ServiceMock<DiscoveryService>;
   }
+  export function events(): EventsService;
   // (undocumented)
   export namespace events {
-    const // (undocumented)
-      factory: () => ServiceFactory<EventsService, 'plugin', 'singleton'>;
-    const // (undocumented)
-      mock: (
-        partialImpl?: Partial<EventsService> | undefined,
-      ) => ServiceMock<EventsService>;
+    const factory: () => ServiceFactory<
+      EventsService,
+      'plugin',
+      'singleton' | 'multiton'
+    >;
+    const mock: (
+      partialImpl?: Partial<EventsService> | undefined,
+    ) => ServiceMock<EventsService>;
   }
   export function httpAuth(options?: {
     pluginId?: string;

packages/backend-test-utils/src/next/services/MockEventsService.test.ts

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2025 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { MockEventsService } from './MockEventsService';
+
+describe('MockEventsService', () => {
+  it('notifies subscribers', async () => {
+    const service = new MockEventsService();
+
+    const listener1 = jest.fn();
+    const listener2 = jest.fn();
+
+    await service.subscribe({
+      id: 'a',
+      topics: ['topic1'],
+      onEvent: listener1,
+    });
+    await service.subscribe({
+      id: 'b',
+      topics: ['topic1', 'topic2'],
+      onEvent: listener2,
+    });
+
+    expect(listener1).not.toHaveBeenCalled();
+    expect(listener2).not.toHaveBeenCalled();
+
+    await service.publish({
+      topic: 'topic1',
+      eventPayload: { payload: 1 },
+    });
+
+    expect(listener1).toHaveBeenCalledTimes(1);
+    expect(listener2).toHaveBeenCalledTimes(1);
+
+    await service.publish({
+      topic: 'topic2',
+      eventPayload: { payload: 1 },
+    });
+
+    expect(listener1).toHaveBeenCalledTimes(1);
+    expect(listener2).toHaveBeenCalledTimes(2);
+  });
+});

packages/backend-test-utils/src/next/services/MockEventsService.ts

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2025 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  EventParams,
+  EventsService,
+  EventsServiceSubscribeOptions,
+} from '@backstage/plugin-events-node';
+
+export class MockEventsService implements EventsService {
+  #subscribers: EventsServiceSubscribeOptions[];
+
+  constructor() {
+    this.#subscribers = [];
+  }
+
+  async publish(params: EventParams): Promise<void> {
+    for (const subscriber of this.#subscribers) {
+      if (subscriber.topics.includes(params.topic)) {
+        await subscriber.onEvent(params);
+      }
+    }
+  }
+
+  async subscribe(options: EventsServiceSubscribeOptions): Promise<void> {
+    this.#subscribers.push(options);
+  }
+}

packages/backend-test-utils/src/next/services/mockServices.ts

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import { auditorServiceFactory } from '@backstage/backend-defaults/auditor';
 import { cacheServiceFactory } from '@backstage/backend-defaults/cache';
 import { databaseServiceFactory } from '@backstage/backend-defaults/database';
 import { HostDiscovery } from '@backstage/backend-defaults/discovery';
@@ -43,10 +44,7 @@ import {
   createServiceFactory,
 } from '@backstage/backend-plugin-api';
 import { ConfigReader } from '@backstage/config';
-import {
-  eventsServiceFactory,
-  eventsServiceRef,
-} from '@backstage/plugin-events-node';
+import { EventsService, eventsServiceRef } from '@backstage/plugin-events-node';
 import { JsonObject } from '@backstage/types';
 import { Knex } from 'knex';
 import { MockAuthService } from './MockAuthService';
@@ -54,7 +52,7 @@ import { MockHttpAuthService } from './MockHttpAuthService';
 import { MockRootLoggerService } from './MockRootLoggerService';
 import { MockUserInfoService } from './MockUserInfoService';
 import { mockCredentials } from './mockCredentials';
-import { auditorServiceFactory } from '@backstage/backend-defaults/auditor';
+import { MockEventsService } from './MockEventsService';
 
 /** @internal */
 function createLoggerMock() {
@@ -521,8 +519,24 @@ export namespace mockServices {
     }));
   }
 
+  /**
+   * Creates a functional mock implementation of the
+   * {@link @backstage/backend-events-node#eventsServiceRef}.
+   */
+  export function events(): EventsService {
+    return new MockEventsService();
+  }
   export namespace events {
-    export const factory = () => eventsServiceFactory;
+    /**
+     * Creates a functional mock factory for the
+     * {@link @backstage/backend-events-node#eventsServiceRef}.
+     */
+    export const factory = simpleFactoryWithOptions(eventsServiceRef, events);
+    /**
+     * Creates a mock of the
+     * {@link @backstage/backend-events-node#eventsServiceRef}, optionally
+     * with some given method implementations.
+     */
     export const mock = simpleMock(eventsServiceRef, () => ({
       publish: jest.fn(),
       subscribe: jest.fn(),