Allow FactRetrieverRegistry to be passed in to context builder for more flexibility

Signed-off-by: sblausten <sam@roadie.io>

plugins/tech-insights-backend/src/service/techInsightsContextBuilder.test.ts

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2022 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 { buildTechInsightsContext } from './techInsightsContextBuilder';
+import {
+  DatabaseManager,
+  getVoidLogger,
+  PluginDatabaseManager,
+  ServerTokenManager,
+} from '@backstage/backend-common';
+import { ConfigReader } from '@backstage/config';
+import { TaskScheduler } from '@backstage/backend-tasks';
+import { FactRetrieverRegistry } from './fact/FactRetrieverRegistry';
+
+jest.mock('./fact/FactRetrieverRegistry');
+
+describe('buildTechInsightsContext', () => {
+  const pluginDatabase = {} as PluginDatabaseManager;
+  const manager = {} as DatabaseManager;
+  const discoveryMock = {
+    getBaseUrl: (_: string) => Promise.resolve('http://mock.url'),
+    getExternalBaseUrl: (_: string) => Promise.resolve('http://mock.url'),
+  };
+  const scheduler = new TaskScheduler(manager, getVoidLogger()).forPlugin(
+    'tech-insights',
+  );
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('constructs the default FactRetrieverRegistry if factRetrievers but no factRetrieverRegistry are passed in', () => {
+    buildTechInsightsContext({
+      database: pluginDatabase,
+      logger: getVoidLogger(),
+      factRetrievers: [],
+      scheduler: scheduler,
+      config: ConfigReader.fromConfigs([]),
+      discovery: discoveryMock,
+      tokenManager: ServerTokenManager.noop(),
+    });
+
+    expect(FactRetrieverRegistry).toHaveBeenCalledTimes(1);
+  });
+
+  it('uses factRetrieverRegistry implementation instead of the default FactRetrieverRegistry if it is passed in', () => {
+    const factRetrieverRegistryMock = {} as FactRetrieverRegistry;
+
+    buildTechInsightsContext({
+      database: pluginDatabase,
+      logger: getVoidLogger(),
+      factRetrievers: [],
+      factRetrieverRegistry: factRetrieverRegistryMock,
+      scheduler: scheduler,
+      config: ConfigReader.fromConfigs([]),
+      discovery: discoveryMock,
+      tokenManager: ServerTokenManager.noop(),
+    });
+
+    expect(FactRetrieverRegistry).not.toHaveBeenCalled();
+  });
+});

plugins/tech-insights-backend/src/service/techInsightsContextBuilder.ts

@@ -52,13 +52,15 @@ export interface TechInsightsOptions<
    * A collection of FactRetrieverRegistrations.
    * Used to register FactRetrievers and their schemas and schedule an execution loop for them.
    */
-  factRetrievers: FactRetrieverRegistration[];
+  factRetrievers?: FactRetrieverRegistration[];
 
   /**
    * Optional factory exposing a `construct` method to initialize a FactChecker implementation
    */
   factCheckerFactory?: FactCheckerFactory<CheckType, CheckResultType>;
 
+  factRetrieverRegistry?: FactRetrieverRegistry;
+
   logger: Logger;
   config: Config;
   discovery: PluginEndpointDiscovery;
@@ -109,7 +111,19 @@ export const buildTechInsightsContext = async <
     tokenManager,
   } = options;
 
-  const factRetrieverRegistry = new FactRetrieverRegistry(factRetrievers);
+  const buildFactRetrieverRegistry = () => {
+    if (!options.factRetrieverRegistry) {
+      if (!factRetrievers) {
+        throw new Error(
+          'Failed to build FactRetrieverRegistry because no factRetrievers found',
+        );
+      }
+      return new FactRetrieverRegistry(factRetrievers);
+    }
+    return options.factRetrieverRegistry;
+  };
+
+  const factRetrieverRegistry = buildFactRetrieverRegistry();
 
   const persistenceContext = await initializePersistenceContext(
     await database.getClient(),