Implement cancelTask in MockSchedulerService with proper error types

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Fredrik Adelöw <freben@spotify.com>

packages/backend-plugin-api/report.api.md

@@ -643,6 +643,7 @@ export interface RootServiceFactoryOptions<
 
 // @public
 export interface SchedulerService {
+  cancelTask(id: string): Promise<void>;
   createScheduledTaskRunner(
     schedule: SchedulerServiceTaskScheduleDefinition,
   ): SchedulerServiceTaskRunner;

packages/backend-test-utils/src/services/MockSchedulerService.ts

@@ -23,6 +23,7 @@ import {
   SchedulerServiceTaskRunner,
   SchedulerServiceTaskScheduleDefinition,
 } from '@backstage/backend-plugin-api';
+import { ConflictError, NotFoundError } from '@backstage/errors';
 import { createDeferred, DeferredPromise } from '@backstage/types';
 
 export class MockSchedulerService implements SchedulerService {
@@ -95,14 +96,21 @@ export class MockSchedulerService implements SchedulerService {
     });
   }
 
-  async cancelTask(_id: string): Promise<void> {
-    // No-op in mock
+  async cancelTask(id: string): Promise<void> {
+    const task = this.#tasks.get(id);
+    if (!task) {
+      throw new NotFoundError(`Task ${id} not found`);
+    }
+    if (!this.#runningTasks.has(id)) {
+      throw new ConflictError(`Task ${id} is not running`);
+    }
+    task.abortControllers.abort();
   }
 
   async triggerTask(id: string): Promise<void> {
     const task = this.#tasks.get(id);
     if (!task) {
-      throw new Error(`Task ${id} not found`);
+      throw new NotFoundError(`Task ${id} not found`);
     }
     if (this.#runningTasks.has(id)) {
       return;