Add tests to demonstrate a race condition in EntityListProvider

Signed-off-by: Jacob Raihle kdm951 <jacob.raihle@teliacompany.com>

plugins/catalog-react/src/hooks/useEntityListProvider.test.tsx

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { catalogApiMock } from '@backstage/plugin-catalog-react/testUtils';
+import type { GetEntitiesResponse } from '@backstage/catalog-client';
 import { Entity } from '@backstage/catalog-model';
 import {
   alertApiRef,
@@ -23,7 +23,10 @@ import {
   identityApiRef,
   storageApiRef,
 } from '@backstage/core-plugin-api';
+import { translationApiRef } from '@backstage/core-plugin-api/alpha';
+import { catalogApiMock } from '@backstage/plugin-catalog-react/testUtils';
 import { mockApis, TestApiProvider } from '@backstage/test-utils';
+import { useMountEffect } from '@react-hookz/web';
 import { act, renderHook, waitFor } from '@testing-library/react';
 import qs from 'qs';
 import { PropsWithChildren } from 'react';
@@ -37,10 +40,9 @@ import {
   EntityTypeFilter,
   EntityUserFilter,
 } from '../filters';
-import { EntityListProvider, useEntityList } from './useEntityListProvider';
-import { useMountEffect } from '@react-hookz/web';
-import { translationApiRef } from '@backstage/core-plugin-api/alpha';
+import { MockPromise } from '../testUtils/MockPromise';
 import { EntityListPagination } from '../types';
+import { EntityListProvider, useEntityList } from './useEntityListProvider';
 
 const entities: Entity[] = [
   {
@@ -341,6 +343,62 @@ describe('<EntityListProvider />', () => {
       filter: { kind: 'group' },
     });
   });
+
+  it('uses the last applied filter even if an earlier request finishes later', async () => {
+    const { result } = renderHook(() => useEntityList(), {
+      wrapper: createWrapper({ pagination }),
+    });
+
+    const firstResult = new MockPromise<GetEntitiesResponse>();
+    const secondResult = new MockPromise<GetEntitiesResponse>();
+
+    await waitFor(() => {
+      expect(result.current.backendEntities.length).toBeGreaterThan(0);
+    });
+    expect(result.current.totalItems).toBe(2);
+    expect(result.current.backendEntities.length).toBe(2);
+    expect(mockCatalogApi.getEntities).toHaveBeenCalledTimes(1);
+
+    mockCatalogApi.getEntities!.mockReturnValueOnce(firstResult);
+
+    await act(async () => {
+      result.current.updateFilters({
+        kind: new EntityKindFilter('api', 'API'),
+      });
+    });
+
+    await waitFor(() => {
+      expect(mockCatalogApi.getEntities).toHaveBeenNthCalledWith(2, {
+        filter: { kind: 'api' },
+      });
+    });
+
+    mockCatalogApi.getEntities!.mockReturnValueOnce(secondResult);
+
+    await act(async () => {
+      result.current.updateFilters({
+        kind: new EntityKindFilter('system', 'System'),
+      });
+    });
+
+    await waitFor(() => {
+      expect(mockCatalogApi.getEntities).toHaveBeenNthCalledWith(3, {
+        filter: { kind: 'system' },
+      });
+    });
+
+    await act(async () => {
+      secondResult.resolve({
+        items: [],
+      });
+      firstResult.resolve({
+        items: entities,
+      });
+    });
+
+    expect(result.current.filters.kind!.value).toBe('system');
+    expect(result.current.backendEntities.length).toBe(0);
+  });
 });
 
 describe('<EntityListProvider pagination />', () => {

plugins/catalog-react/src/testUtils/MockPromise.test.ts

@@ -0,0 +1,31 @@
+/*
+ * 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 { MockPromise } from './MockPromise.ts';
+
+describe('MockPromise', () => {
+  it('is resolved when its resolve function is called', async () => {
+    const p = new MockPromise<number>();
+    p.resolve(12);
+    return expect(p).resolves.toBe(12);
+  });
+
+  it('is rejected when its reject function is called', async () => {
+    const p = new MockPromise();
+    p.reject('Test rejection');
+    return expect(p).rejects.toMatch('Test rejection');
+  });
+});

plugins/catalog-react/src/testUtils/MockPromise.ts

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ */
+type ResolveFn<T> = (value: T | PromiseLike<T>) => void;
+type RejectFn = (reason?: any) => void;
+type Executor<T> = (resolve: ResolveFn<T>, reject: RejectFn) => void;
+
+export class MockPromise<T> extends Promise<T> {
+  private _resolve!: ResolveFn<T>;
+  private _reject!: RejectFn;
+
+  constructor(executor?: Executor<T>) {
+    if (executor !== undefined) {
+      super(executor);
+      return;
+    }
+
+    let res: ResolveFn<T>;
+    let rej: RejectFn;
+    super((resolve, reject) => {
+      res = resolve;
+      rej = reject;
+    });
+    this._resolve = res!;
+    this._reject = rej!;
+  }
+
+  get resolve() {
+    return this._resolve;
+  }
+
+  get reject() {
+    return this._reject;
+  }
+}