add featureDiscoveryServiceFactory test

Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>
Signed-off-by: Vincenzo Scamporlino <vincenzos@spotify.com>

packages/backend-app-api/package.json

@@ -12,13 +12,13 @@
   },
   "exports": {
     ".": "./src/index.ts",
-    "./alpha": "./src/alpha.ts",
+    "./alpha": "./src/alpha/index.ts",
     "./package.json": "./package.json"
   },
   "typesVersions": {
     "*": {
       "alpha": [
-        "src/alpha.ts"
+        "src/alpha/index.ts"
       ],
       "package.json": [
         "package.json"
@@ -87,6 +87,7 @@
     "@types/node-forge": "^1.3.0",
     "@types/stoppable": "^1.1.0",
     "http-errors": "^2.0.0",
+    "mock-fs": "^5.2.0",
     "supertest": "^6.1.3"
   },
   "files": [

packages/backend-app-api/src/alpha.ts

@@ -1,17 +0,0 @@
-/*
- * Copyright 2023 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.
- */
-
-export * from './alpha';

packages/backend-app-api/src/alpha/featureDiscoveryServiceFactory.test.ts

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2023 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 mockFs from 'mock-fs';
+import { resolve as resolvePath, dirname } from 'path';
+import { startTestBackend, mockServices } from '@backstage/backend-test-utils';
+import { featureDiscoveryServiceFactory } from './featureDiscoveryServiceFactory';
+import {
+  coreServices,
+  createServiceFactory,
+} from '@backstage/backend-plugin-api';
+
+const rootDir = dirname(process.argv[1]);
+
+describe('featureDiscoveryServiceFactory', () => {
+  beforeEach(() => {
+    mockFs({
+      [rootDir]: {
+        'package.json': JSON.stringify({
+          name: 'example-app',
+          dependencies: {
+            'detected-plugin': '0.0.0',
+            'detected-module': '0.0.0',
+          },
+        }),
+      },
+      [resolvePath(rootDir, 'node_modules/detected-plugin')]: {
+        'package.json': JSON.stringify({
+          name: 'detected-plugin',
+          main: 'index.js',
+          backstage: {
+            role: 'backend-plugin',
+          },
+        }),
+        'index.js': `
+        const { createBackendPlugin, coreServices } = require('@backstage/backend-plugin-api');
+        exports.detectedPlugin = createBackendPlugin({
+            pluginId: 'detected',
+            register(env) {
+              env.registerInit({
+                deps: { identity: coreServices.identity },
+                async init({ identity }) {
+                  identity.getIdentity('detected-plugin');
+                },
+              });
+            },
+        });
+        `,
+      },
+      [resolvePath(rootDir, 'node_modules/detected-module')]: {
+        'package.json': JSON.stringify({
+          name: 'detected-module',
+          main: 'index.js',
+          backstage: {
+            role: 'backend-module',
+          },
+        }),
+        'index.js': `
+        const { createBackendModule, coreServices } = require('@backstage/backend-plugin-api');
+        exports.detectedModuleDerp = createBackendModule({
+            pluginId: 'detected',
+            moduleId: 'derp',
+            register(env) {
+              env.registerInit({
+                deps: { identity: coreServices.identity },
+                async init({ identity }) {
+                  identity.getIdentity('detected-module');
+                },
+              });
+            },
+        });
+        `,
+      },
+    });
+  });
+
+  afterEach(() => {
+    mockFs.restore();
+  });
+
+  it('should detect plugin and module packages', async () => {
+    const fn = jest.fn().mockResolvedValue({});
+
+    await startTestBackend({
+      services: [
+        createServiceFactory({
+          service: coreServices.identity,
+          deps: {},
+          factory: () => ({ getIdentity: fn }),
+        }),
+        featureDiscoveryServiceFactory(),
+        mockServices.rootConfig.factory({
+          data: { backend: { packages: 'all' } },
+        }),
+      ],
+    });
+
+    expect(fn).toHaveBeenCalledWith('detected-plugin');
+    expect(fn).toHaveBeenCalledWith('detected-module');
+  });
+});

packages/backend-app-api/src/alpha/featureDiscoveryServiceFactory.ts

@@ -79,11 +79,13 @@ class PackageDiscoveryService implements FeatureDiscoveryService {
     const features: BackendFeature[] = [];
 
     for (const name of dependencyNames) {
-      const depPkg = require(`${name}/package.json`) as BackstagePackageJson;
+      const depPkg = require(require.resolve(`${name}/package.json`, {
+        paths: [packageDir],
+      })) as BackstagePackageJson;
       if (!LOADED_PACKAGE_ROLES.includes(depPkg?.backstage?.role ?? '')) {
         continue;
       }
-      const depModule = require(name);
+      const depModule = require(require.resolve(name, { paths: [packageDir] }));
       for (const exportValue of Object.values(depModule)) {
         if (isBackendFeature(exportValue)) {
           features.push(exportValue);
@@ -122,7 +124,7 @@ function isBackendFeatureFactory(
 ): value is BackendFeatureFactory {
   return (
     !!value &&
-    typeof value === 'object' &&
+    typeof value === 'function' &&
     (value as BackendFeatureFactory).$$type ===
       '@backstage/BackendFeatureFactory'
   );

packages/backend-plugin-api/src/alpha.ts

@@ -22,7 +22,10 @@ export interface FeatureDiscoveryService {
   getBackendFeatures(): Promise<{ features: Array<BackendFeature> }>;
 }
 
-/** @alpha */
+/**
+ * An optional service that can be used to dynamically load in additional BackendFeatures at runtime.
+ * @alpha
+ */
 export const featureDiscoveryServiceRef =
   createServiceRef<FeatureDiscoveryService>({
     id: 'core.featureDiscovery',

yarn.lock

@@ -3320,6 +3320,7 @@ __metadata:
     logform: ^2.3.2
     minimatch: ^5.0.0
     minimist: ^1.2.5
+    mock-fs: ^5.2.0
     morgan: ^1.10.0
     node-forge: ^1.3.1
     selfsigned: ^2.0.0