Use mockCredentials in CachedEntityLoader tests and simplify cache key

Replace hand-crafted BackstageCredentials objects with mockCredentials
from @backstage/backend-test-utils, which have proper toString() methods.
Simplify getCacheKey to use String(credentials) directly and remove the
auth service dependency from CachedEntityLoader.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Made-with: Cursor

plugins/techdocs-backend/src/service/CachedEntityLoader.test.ts

@@ -16,13 +16,11 @@
 
 import { CachedEntityLoader } from './CachedEntityLoader';
 import { CompoundEntityRef } from '@backstage/catalog-model';
-import { mockServices } from '@backstage/backend-test-utils';
+import { mockCredentials, mockServices } from '@backstage/backend-test-utils';
 import { catalogServiceMock } from '@backstage/plugin-catalog-node/testUtils';
-import { BackstageCredentials } from '@backstage/backend-plugin-api';
 
 describe('CachedEntityLoader', () => {
   const cache = mockServices.cache.mock();
-  const auth = mockServices.auth.mock();
 
   const entityName: CompoundEntityRef = {
     kind: 'component',
@@ -39,21 +37,8 @@ describe('CachedEntityLoader', () => {
     },
   };
 
-  const userCredentials: BackstageCredentials = {
-    $$type: '@backstage/BackstageCredentials',
-    principal: {
-      type: 'user',
-      userEntityRef: 'user:default/test-user',
-    },
-  };
-
-  const pluginCredentials: BackstageCredentials = {
-    $$type: '@backstage/BackstageCredentials',
-    principal: {
-      type: 'plugin',
-      subject: 'plugin:test-plugin',
-    },
-  };
+  const userCredentials = mockCredentials.user('user:default/test-user');
+  const serviceCredentials = mockCredentials.service('plugin:test-plugin');
 
   afterEach(() => {
     jest.resetAllMocks();
@@ -63,9 +48,8 @@ describe('CachedEntityLoader', () => {
     cache.get.mockResolvedValue(undefined);
     const catalog = catalogServiceMock({ entities: [entity] });
     jest.spyOn(catalog, 'getEntityByRef');
-    auth.isPrincipal.mockReturnValue(true);
 
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
+    const loader = new CachedEntityLoader({ catalog, cache });
     const result = await loader.load(userCredentials, entityName);
 
     expect(result).toEqual(entity);
@@ -73,7 +57,7 @@ describe('CachedEntityLoader', () => {
       credentials: userCredentials,
     });
     expect(cache.set).toHaveBeenCalledWith(
-      'catalog:component:default/test:user:default/test-user',
+      `catalog:component:default/test:${userCredentials}`,
       entity,
       { ttl: 5000 },
     );
@@ -83,9 +67,8 @@ describe('CachedEntityLoader', () => {
     const catalog = catalogServiceMock();
     jest.spyOn(catalog, 'getEntityByRef');
     cache.get.mockResolvedValue(entity);
-    auth.isPrincipal.mockReturnValue(true);
 
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
+    const loader = new CachedEntityLoader({ catalog, cache });
     const result = await loader.load(userCredentials, entityName);
 
     expect(result).toEqual(entity);
@@ -95,33 +78,14 @@ describe('CachedEntityLoader', () => {
   it('does not cache missing entities', async () => {
     const catalog = catalogServiceMock({ entities: [] });
     cache.get.mockResolvedValue(undefined);
-    auth.isPrincipal.mockReturnValue(true);
 
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
+    const loader = new CachedEntityLoader({ catalog, cache });
     const result = await loader.load(userCredentials, entityName);
 
     expect(result).toBeUndefined();
     expect(cache.set).not.toHaveBeenCalled();
   });
 
-  it('uses entity ref as cache key for service credentials', async () => {
-    const catalog = catalogServiceMock({ entities: [entity] });
-    cache.get.mockResolvedValue(undefined);
-    auth.isPrincipal.mockReturnValueOnce(false).mockReturnValueOnce(true);
-
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
-    const result = await loader.load(pluginCredentials, entityName);
-
-    expect(result).toEqual(entity);
-    expect(cache.set).toHaveBeenCalledWith(
-      'catalog:component:default/test:plugin:test-plugin',
-      entity,
-      {
-        ttl: 5000,
-      },
-    );
-  });
-
   it('calls the catalog if the cache read takes too long', async () => {
     cache.get.mockImplementation(
       () =>
@@ -130,80 +94,48 @@ describe('CachedEntityLoader', () => {
         }),
     );
     const catalog = catalogServiceMock({ entities: [entity] });
-    auth.isPrincipal.mockReturnValue(true);
 
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
+    const loader = new CachedEntityLoader({ catalog, cache });
     const result = await loader.load(userCredentials, entityName);
 
     expect(result).toEqual(entity);
   });
 
-  it('creates different cache keys for different users', async () => {
+  it('creates different cache keys for different credentials', async () => {
     const catalog = catalogServiceMock({ entities: [entity] });
     cache.get.mockResolvedValue(undefined);
-    auth.isPrincipal.mockReturnValue(true);
 
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
+    const loader = new CachedEntityLoader({ catalog, cache });
 
-    const anotherUserCredentials: BackstageCredentials = {
-      $$type: '@backstage/BackstageCredentials',
-      principal: {
-        type: 'user',
-        userEntityRef: 'user:default/another-user',
-      },
-    };
+    const anotherUserCredentials = mockCredentials.user(
+      'user:default/another-user',
+    );
 
     await loader.load(userCredentials, entityName);
     await loader.load(anotherUserCredentials, entityName);
 
     expect(cache.set).toHaveBeenCalledWith(
-      'catalog:component:default/test:user:default/test-user',
+      `catalog:component:default/test:${userCredentials}`,
       entity,
       { ttl: 5000 },
     );
     expect(cache.set).toHaveBeenCalledWith(
-      'catalog:component:default/test:user:default/another-user',
+      `catalog:component:default/test:${anotherUserCredentials}`,
       entity,
       { ttl: 5000 },
     );
   });
 
-  it('creates cache key with service subject for service credentials', async () => {
+  it('uses service credentials as cache key for service credentials', async () => {
     const catalog = catalogServiceMock({ entities: [entity] });
     cache.get.mockResolvedValue(undefined);
-    auth.isPrincipal.mockReturnValueOnce(false).mockReturnValueOnce(true);
 
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
-    const result = await loader.load(pluginCredentials, entityName);
+    const loader = new CachedEntityLoader({ catalog, cache });
+    const result = await loader.load(serviceCredentials, entityName);
 
     expect(result).toEqual(entity);
     expect(cache.set).toHaveBeenCalledWith(
-      'catalog:component:default/test:plugin:test-plugin',
-      entity,
-      { ttl: 5000 },
-    );
-    expect(auth.isPrincipal).toHaveBeenCalledWith(pluginCredentials, 'user');
-    expect(auth.isPrincipal).toHaveBeenCalledWith(pluginCredentials, 'service');
-  });
-
-  it('handles credentials that are neither user nor service', async () => {
-    const catalog = catalogServiceMock({ entities: [entity] });
-    cache.get.mockResolvedValue(undefined);
-    auth.isPrincipal.mockReturnValue(false);
-
-    const unknownCredentials: BackstageCredentials = {
-      $$type: '@backstage/BackstageCredentials',
-      principal: {
-        type: 'unknown' as any,
-      },
-    };
-
-    const loader = new CachedEntityLoader({ auth, catalog, cache });
-    const result = await loader.load(unknownCredentials, entityName);
-
-    expect(result).toEqual(entity);
-    expect(cache.set).toHaveBeenCalledWith(
-      'catalog:component:default/test',
+      `catalog:component:default/test:${serviceCredentials}`,
       entity,
       { ttl: 5000 },
     );

plugins/techdocs-backend/src/service/CachedEntityLoader.ts

@@ -15,7 +15,6 @@
  */
 
 import {
-  AuthService,
   BackstageCredentials,
   CacheService,
 } from '@backstage/backend-plugin-api';
@@ -27,19 +26,16 @@ import {
 import { CatalogService } from '@backstage/plugin-catalog-node';
 
 export type CachedEntityLoaderOptions = {
-  auth: AuthService;
   catalog: CatalogService;
   cache: CacheService;
 };
 
 export class CachedEntityLoader {
-  private readonly auth: AuthService;
   private readonly catalog: CatalogService;
   private readonly cache: CacheService;
   private readonly readTimeout = 1000;
 
-  constructor({ auth, catalog, cache }: CachedEntityLoaderOptions) {
-    this.auth = auth;
+  constructor({ catalog, cache }: CachedEntityLoaderOptions) {
     this.catalog = catalog;
     this.cache = cache;
   }
@@ -77,14 +73,10 @@ export class CachedEntityLoader {
     entityName: CompoundEntityRef,
     credentials: BackstageCredentials,
   ): string {
-    const key = ['catalog', stringifyEntityRef(entityName)];
-
-    if (this.auth.isPrincipal(credentials, 'user')) {
-      key.push(credentials.principal.userEntityRef);
-    } else if (this.auth.isPrincipal(credentials, 'service')) {
-      key.push(credentials.principal.subject);
-    }
-
-    return key.join(':');
+    return [
+      'catalog',
+      stringifyEntityRef(entityName),
+      String(credentials), // these have a well defined toString method
+    ].join(':');
   }
 }

plugins/techdocs-backend/src/service/router.ts

@@ -124,7 +124,6 @@ export async function createRouter(
   // Entities are cached to optimize the /static/docs request path, which can be called many times
   // when loading a single techdocs page.
   const entityLoader = new CachedEntityLoader({
-    auth,
     catalog,
     cache: options.cache,
   });