From e3d514507a88d71cc09ab6d23b14ca8f87fcf23d Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 13:40:59 +0200
Subject: [PATCH 1/9] backend-app-api: rename BackendRegistrable to
 BackendFeature
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>
Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../src/wiring/BackendInitializer.ts          | 22 +++++++++----------
 .../src/wiring/BackstageBackend.ts            |  6 ++---
 packages/backend-app-api/src/wiring/types.ts  |  4 ++--
 .../src/wiring/factories.ts                   | 14 +++++-------
 .../backend-plugin-api/src/wiring/index.ts    |  2 +-
 .../backend-plugin-api/src/wiring/types.ts    |  2 +-
 .../src/next/wiring/TestBackend.ts            |  4 ++--
 7 files changed, 24 insertions(+), 30 deletions(-)

diff --git a/packages/backend-app-api/src/wiring/BackendInitializer.ts b/packages/backend-app-api/src/wiring/BackendInitializer.ts
index ab086f4144..0c2cd3e541 100644
--- a/packages/backend-app-api/src/wiring/BackendInitializer.ts
+++ b/packages/backend-app-api/src/wiring/BackendInitializer.ts
@@ -15,7 +15,7 @@
  */
 
 import {
-  BackendRegistrable,
+  BackendFeature,
   ExtensionPoint,
   ServiceRef,
 } from '@backstage/backend-plugin-api';
@@ -25,7 +25,7 @@ type ServiceOrExtensionPoint = ExtensionPoint<unknown> | ServiceRef<unknown>;
 
 export class BackendInitializer {
   #started = false;
-  #extensions = new Map<BackendRegistrable, unknown>();
+  #features = new Map<BackendFeature, unknown>();
   #registerInits = new Array<BackendRegisterInit>();
   #extensionPoints = new Map<ServiceOrExtensionPoint, unknown>();
   #serviceHolder: ServiceHolder;
@@ -51,13 +51,11 @@ export class BackendInitializer {
     );
   }
 
-  add<TOptions>(extension: BackendRegistrable, options?: TOptions) {
+  add<TOptions>(feature: BackendFeature, options?: TOptions) {
     if (this.#started) {
-      throw new Error(
-        'extension can not be added after the backend has started',
-      );
+      throw new Error('feature can not be added after the backend has started');
     }
-    this.#extensions.set(extension, options);
+    this.#features.set(feature, options);
   }
 
   async start(): Promise<void> {
@@ -67,13 +65,13 @@ export class BackendInitializer {
     }
     this.#started = true;
 
-    for (const [extension] of this.#extensions) {
+    for (const [feature] of this.#features) {
       const provides = new Set<ServiceRef<unknown>>();
 
       let registerInit: BackendRegisterInit | undefined = undefined;
 
-      console.log('Registering', extension.id);
-      extension.register({
+      console.log('Registering', feature.id);
+      feature.register({
         registerExtensionPoint: (extensionPointRef, impl) => {
           if (registerInit) {
             throw new Error('registerExtensionPoint called after registerInit');
@@ -89,7 +87,7 @@ export class BackendInitializer {
             throw new Error('registerInit must only be called once');
           }
           registerInit = {
-            id: extension.id,
+            id: feature.id,
             provides,
             consumes: new Set(Object.values(registerOptions.deps)),
             deps: registerOptions.deps,
@@ -100,7 +98,7 @@ export class BackendInitializer {
 
       if (!registerInit) {
         throw new Error(
-          `registerInit was not called by register in ${extension.id}`,
+          `registerInit was not called by register in ${feature.id}`,
         );
       }
 
diff --git a/packages/backend-app-api/src/wiring/BackstageBackend.ts b/packages/backend-app-api/src/wiring/BackstageBackend.ts
index 104d2b6fc8..1e09ed77ba 100644
--- a/packages/backend-app-api/src/wiring/BackstageBackend.ts
+++ b/packages/backend-app-api/src/wiring/BackstageBackend.ts
@@ -16,7 +16,7 @@
 
 import {
   AnyServiceFactory,
-  BackendRegistrable,
+  BackendFeature,
 } from '@backstage/backend-plugin-api';
 import { BackendInitializer } from './BackendInitializer';
 import { ServiceRegistry } from './ServiceRegistry';
@@ -31,8 +31,8 @@ export class BackstageBackend implements Backend {
     this.#initializer = new BackendInitializer(this.#services);
   }
 
-  add(extension: BackendRegistrable): void {
-    this.#initializer.add(extension);
+  add(feature: BackendFeature): void {
+    this.#initializer.add(feature);
   }
 
   async start(): Promise<void> {
diff --git a/packages/backend-app-api/src/wiring/types.ts b/packages/backend-app-api/src/wiring/types.ts
index 2aaead805d..cdd4578789 100644
--- a/packages/backend-app-api/src/wiring/types.ts
+++ b/packages/backend-app-api/src/wiring/types.ts
@@ -16,7 +16,7 @@
 
 import {
   AnyServiceFactory,
-  BackendRegistrable,
+  BackendFeature,
   FactoryFunc,
   ServiceRef,
 } from '@backstage/backend-plugin-api';
@@ -26,7 +26,7 @@ import { BackstageBackend } from './BackstageBackend';
  * @public
  */
 export interface Backend {
-  add(extension: BackendRegistrable): void;
+  add(feature: BackendFeature): void;
   start(): Promise<void>;
 }
 
diff --git a/packages/backend-plugin-api/src/wiring/factories.ts b/packages/backend-plugin-api/src/wiring/factories.ts
index 1c3a27bb1c..a057c0d6ec 100644
--- a/packages/backend-plugin-api/src/wiring/factories.ts
+++ b/packages/backend-plugin-api/src/wiring/factories.ts
@@ -14,11 +14,7 @@
  * limitations under the License.
  */
 
-import {
-  BackendInitRegistry,
-  BackendRegistrable,
-  ExtensionPoint,
-} from './types';
+import { BackendInitRegistry, BackendFeature, ExtensionPoint } from './types';
 
 /** @public */
 export function createExtensionPoint<T>(options: {
@@ -46,8 +42,8 @@ export interface BackendPluginConfig<TOptions> {
 export function createBackendPlugin<TOptions>(
   config: BackendPluginConfig<TOptions>,
 ): undefined extends TOptions
-  ? (options?: TOptions) => BackendRegistrable
-  : (options: TOptions) => BackendRegistrable {
+  ? (options?: TOptions) => BackendFeature
+  : (options: TOptions) => BackendFeature {
   return (options?: TOptions) => ({
     id: config.id,
     register(register: BackendInitRegistry) {
@@ -70,8 +66,8 @@ export interface BackendModuleConfig<TOptions> {
 export function createBackendModule<TOptions>(
   config: BackendModuleConfig<TOptions>,
 ): undefined extends TOptions
-  ? (options?: TOptions) => BackendRegistrable
-  : (options: TOptions) => BackendRegistrable {
+  ? (options?: TOptions) => BackendFeature
+  : (options: TOptions) => BackendFeature {
   return (options?: TOptions) => ({
     id: `${config.pluginId}.${config.moduleId}`,
     register(register: BackendInitRegistry) {
diff --git a/packages/backend-plugin-api/src/wiring/index.ts b/packages/backend-plugin-api/src/wiring/index.ts
index 342a922dbd..2ad414beca 100644
--- a/packages/backend-plugin-api/src/wiring/index.ts
+++ b/packages/backend-plugin-api/src/wiring/index.ts
@@ -22,6 +22,6 @@ export {
 } from './factories';
 export type {
   BackendInitRegistry,
-  BackendRegistrable,
+  BackendFeature,
   ExtensionPoint,
 } from './types';
diff --git a/packages/backend-plugin-api/src/wiring/types.ts b/packages/backend-plugin-api/src/wiring/types.ts
index 65525fd8aa..3f01879f80 100644
--- a/packages/backend-plugin-api/src/wiring/types.ts
+++ b/packages/backend-plugin-api/src/wiring/types.ts
@@ -48,7 +48,7 @@ export interface BackendInitRegistry {
 }
 
 /** @public */
-export interface BackendRegistrable {
+export interface BackendFeature {
   id: string;
   register(reg: BackendInitRegistry): void;
 }
diff --git a/packages/backend-test-utils/src/next/wiring/TestBackend.ts b/packages/backend-test-utils/src/next/wiring/TestBackend.ts
index c7bc987cb8..30dbe7f804 100644
--- a/packages/backend-test-utils/src/next/wiring/TestBackend.ts
+++ b/packages/backend-test-utils/src/next/wiring/TestBackend.ts
@@ -19,7 +19,7 @@ import {
   AnyServiceFactory,
   ServiceRef,
   createServiceFactory,
-  BackendRegistrable,
+  BackendFeature,
 } from '@backstage/backend-plugin-api';
 
 /** @alpha */
@@ -53,7 +53,7 @@ export function createTestBackend<TServices extends any[]>(
 /** @alpha */
 export async function startTestBackend<TServices extends any[]>(
   options: TestBackendOptions<TServices> & {
-    registrables?: BackendRegistrable[];
+    registrables?: BackendFeature[];
   },
 ): Promise<void> {
   const { registrables = [], ...otherOptions } = options;

From 04525293745fdb736d9918042633a3cc9d077c49 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 14:02:15 +0200
Subject: [PATCH 2/9] BackendInitRegistry -> BackendRegistrationPoints
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Fredrik Adelöw <freben@users.noreply.github.com>
Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>
Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../backend-plugin-api/src/wiring/factories.ts     | 14 +++++++++-----
 packages/backend-plugin-api/src/wiring/index.ts    |  2 +-
 packages/backend-plugin-api/src/wiring/types.ts    |  5 +++--
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/packages/backend-plugin-api/src/wiring/factories.ts b/packages/backend-plugin-api/src/wiring/factories.ts
index a057c0d6ec..68f13f6c30 100644
--- a/packages/backend-plugin-api/src/wiring/factories.ts
+++ b/packages/backend-plugin-api/src/wiring/factories.ts
@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
-import { BackendInitRegistry, BackendFeature, ExtensionPoint } from './types';
+import {
+  BackendRegistrationPoints,
+  BackendFeature,
+  ExtensionPoint,
+} from './types';
 
 /** @public */
 export function createExtensionPoint<T>(options: {
@@ -35,7 +39,7 @@ export function createExtensionPoint<T>(options: {
 /** @public */
 export interface BackendPluginConfig<TOptions> {
   id: string;
-  register(reg: BackendInitRegistry, options: TOptions): void;
+  register(reg: BackendRegistrationPoints, options: TOptions): void;
 }
 
 /** @public */
@@ -46,7 +50,7 @@ export function createBackendPlugin<TOptions>(
   : (options: TOptions) => BackendFeature {
   return (options?: TOptions) => ({
     id: config.id,
-    register(register: BackendInitRegistry) {
+    register(register: BackendRegistrationPoints) {
       return config.register(register, options!);
     },
   });
@@ -57,7 +61,7 @@ export interface BackendModuleConfig<TOptions> {
   pluginId: string;
   moduleId: string;
   register(
-    reg: Omit<BackendInitRegistry, 'registerExtensionPoint'>,
+    reg: Omit<BackendRegistrationPoints, 'registerExtensionPoint'>,
     options: TOptions,
   ): void;
 }
@@ -70,7 +74,7 @@ export function createBackendModule<TOptions>(
   : (options: TOptions) => BackendFeature {
   return (options?: TOptions) => ({
     id: `${config.pluginId}.${config.moduleId}`,
-    register(register: BackendInitRegistry) {
+    register(register: BackendRegistrationPoints) {
       // TODO: Hide registerExtensionPoint
       return config.register(register, options!);
     },
diff --git a/packages/backend-plugin-api/src/wiring/index.ts b/packages/backend-plugin-api/src/wiring/index.ts
index 2ad414beca..8f85edb2eb 100644
--- a/packages/backend-plugin-api/src/wiring/index.ts
+++ b/packages/backend-plugin-api/src/wiring/index.ts
@@ -21,7 +21,7 @@ export {
   createExtensionPoint,
 } from './factories';
 export type {
-  BackendInitRegistry,
+  BackendRegistrationPoints,
   BackendFeature,
   ExtensionPoint,
 } from './types';
diff --git a/packages/backend-plugin-api/src/wiring/types.ts b/packages/backend-plugin-api/src/wiring/types.ts
index 3f01879f80..1801127ddb 100644
--- a/packages/backend-plugin-api/src/wiring/types.ts
+++ b/packages/backend-plugin-api/src/wiring/types.ts
@@ -36,7 +36,7 @@ export type ExtensionPoint<T> = {
 };
 
 /** @public */
-export interface BackendInitRegistry {
+export interface BackendRegistrationPoints {
   registerExtensionPoint<TExtensionPoint>(
     ref: ServiceRef<TExtensionPoint>,
     impl: TExtensionPoint,
@@ -49,6 +49,7 @@ export interface BackendInitRegistry {
 
 /** @public */
 export interface BackendFeature {
+  // TODO(Rugvip): Try to get rid of the ID at this level, allowing for a feature to register multiple features as a bundle
   id: string;
-  register(reg: BackendInitRegistry): void;
+  register(reg: BackendRegistrationPoints): void;
 }

From 0ef2719b11ba98a167cfafa86787fd71dfa09c96 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 14:13:02 +0200
Subject: [PATCH 3/9] registrables -> feature
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Fredrik Adelöw <freben@users.noreply.github.com>
Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../backend-test-utils/src/next/wiring/TestBackend.ts     | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/backend-test-utils/src/next/wiring/TestBackend.ts b/packages/backend-test-utils/src/next/wiring/TestBackend.ts
index 30dbe7f804..150d4ce2af 100644
--- a/packages/backend-test-utils/src/next/wiring/TestBackend.ts
+++ b/packages/backend-test-utils/src/next/wiring/TestBackend.ts
@@ -53,13 +53,13 @@ export function createTestBackend<TServices extends any[]>(
 /** @alpha */
 export async function startTestBackend<TServices extends any[]>(
   options: TestBackendOptions<TServices> & {
-    registrables?: BackendFeature[];
+    features?: BackendFeature[];
   },
 ): Promise<void> {
-  const { registrables = [], ...otherOptions } = options;
+  const { features = [], ...otherOptions } = options;
   const backend = createTestBackend(otherOptions);
-  for (const reg of registrables) {
-    backend.add(reg);
+  for (const feature of features) {
+    backend.add(feature);
   }
   await backend.start();
 }

From 0d2e6197d8e775fcf9b146f8b7735d2a45b2f893 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 15:30:24 +0200
Subject: [PATCH 4/9] =?UTF-8?q?Refactor=20backend-test-utils=20Co-authored?=
 =?UTF-8?q?-by:=20Fredrik=20Adel=C3=B6w=20<freben@users.noreply.github.com?=
 =?UTF-8?q?>=20Co-authored-by:=20Patrik=20Oldsberg=20<poldsberg@gmail.com>?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../src/wiring/BackendInitializer.ts          | 21 +++---
 packages/backend-app-api/src/wiring/index.ts  |  6 +-
 packages/backend-app-api/src/wiring/types.ts  | 14 +++-
 .../backend-plugin-api/src/wiring/types.ts    |  8 ++-
 .../src/next/wiring/TestBackend.test.ts       |  6 +-
 .../src/next/wiring/TestBackend.ts            | 64 ++++++++++++++-----
 .../src/next/wiring/index.ts                  |  2 +-
 plugins/catalog-node/src/extensions.ts        |  4 +-
 .../extension/ScaffolderCatalogModule.test.ts |  5 +-
 9 files changed, 89 insertions(+), 41 deletions(-)

diff --git a/packages/backend-app-api/src/wiring/BackendInitializer.ts b/packages/backend-app-api/src/wiring/BackendInitializer.ts
index 0c2cd3e541..c1b7089827 100644
--- a/packages/backend-app-api/src/wiring/BackendInitializer.ts
+++ b/packages/backend-app-api/src/wiring/BackendInitializer.ts
@@ -19,15 +19,17 @@ import {
   ExtensionPoint,
   ServiceRef,
 } from '@backstage/backend-plugin-api';
-import { BackendRegisterInit, ServiceHolder } from './types';
-
-type ServiceOrExtensionPoint = ExtensionPoint<unknown> | ServiceRef<unknown>;
+import {
+  BackendRegisterInit,
+  ServiceHolder,
+  ServiceOrExtensionPoint,
+} from './types';
 
 export class BackendInitializer {
   #started = false;
   #features = new Map<BackendFeature, unknown>();
   #registerInits = new Array<BackendRegisterInit>();
-  #extensionPoints = new Map<ServiceOrExtensionPoint, unknown>();
+  #extensionPoints = new Map<ExtensionPoint<unknown>, unknown>();
   #serviceHolder: ServiceHolder;
 
   constructor(serviceHolder: ServiceHolder) {
@@ -42,7 +44,7 @@ export class BackendInitializer {
       await Promise.all(
         Object.entries(deps).map(async ([name, ref]) => [
           name,
-          this.#extensionPoints.get(ref) ||
+          this.#extensionPoints.get(ref as ExtensionPoint<unknown>) ||
             (await this.#serviceHolder.get(ref as ServiceRef<unknown>)!(
               pluginId,
             )),
@@ -66,7 +68,7 @@ export class BackendInitializer {
     this.#started = true;
 
     for (const [feature] of this.#features) {
-      const provides = new Set<ServiceRef<unknown>>();
+      const provides = new Set<ExtensionPoint<unknown>>();
 
       let registerInit: BackendRegisterInit | undefined = undefined;
 
@@ -129,13 +131,13 @@ export class BackendInitializer {
       for (const registerInit of registerInitsToOrder) {
         const unInitializedDependents = [];
 
-        for (const serviceRef of registerInit.provides) {
+        for (const provided of registerInit.provides) {
           if (
             registerInitsToOrder.some(
-              init => init !== registerInit && init.consumes.has(serviceRef),
+              init => init !== registerInit && init.consumes.has(provided),
             )
           ) {
-            unInitializedDependents.push(serviceRef);
+            unInitializedDependents.push(provided);
           }
         }
 
@@ -148,6 +150,7 @@ export class BackendInitializer {
 
       registerInitsToOrder = registerInitsToOrder.filter(r => !toRemove.has(r));
     }
+
     return orderedRegisterInits;
   }
 }
diff --git a/packages/backend-app-api/src/wiring/index.ts b/packages/backend-app-api/src/wiring/index.ts
index d6e4de9145..2f55076922 100644
--- a/packages/backend-app-api/src/wiring/index.ts
+++ b/packages/backend-app-api/src/wiring/index.ts
@@ -14,5 +14,9 @@
  * limitations under the License.
  */
 
-export type { Backend, CreateSpecializedBackendOptions } from './types';
+export type {
+  Backend,
+  CreateSpecializedBackendOptions,
+  ServiceOrExtensionPoint,
+} from './types';
 export { createSpecializedBackend } from './types';
diff --git a/packages/backend-app-api/src/wiring/types.ts b/packages/backend-app-api/src/wiring/types.ts
index cdd4578789..0ca40b5660 100644
--- a/packages/backend-app-api/src/wiring/types.ts
+++ b/packages/backend-app-api/src/wiring/types.ts
@@ -17,6 +17,7 @@
 import {
   AnyServiceFactory,
   BackendFeature,
+  ExtensionPoint,
   FactoryFunc,
   ServiceRef,
 } from '@backstage/backend-plugin-api';
@@ -32,9 +33,9 @@ export interface Backend {
 
 export interface BackendRegisterInit {
   id: string;
-  consumes: Set<ServiceRef<unknown>>;
-  provides: Set<ServiceRef<unknown>>;
-  deps: { [name: string]: ServiceRef<unknown> };
+  consumes: Set<ServiceOrExtensionPoint>;
+  provides: Set<ServiceOrExtensionPoint>;
+  deps: { [name: string]: ServiceOrExtensionPoint };
   init: (deps: { [name: string]: unknown }) => Promise<void>;
 }
 
@@ -57,3 +58,10 @@ export function createSpecializedBackend(
 ): Backend {
   return new BackstageBackend(options.services);
 }
+
+/**
+ * @public
+ */
+export type ServiceOrExtensionPoint<T = unknown> =
+  | ExtensionPoint<T>
+  | ServiceRef<T>;
diff --git a/packages/backend-plugin-api/src/wiring/types.ts b/packages/backend-plugin-api/src/wiring/types.ts
index 1801127ddb..cdb56ea2e4 100644
--- a/packages/backend-plugin-api/src/wiring/types.ts
+++ b/packages/backend-plugin-api/src/wiring/types.ts
@@ -38,12 +38,14 @@ export type ExtensionPoint<T> = {
 /** @public */
 export interface BackendRegistrationPoints {
   registerExtensionPoint<TExtensionPoint>(
-    ref: ServiceRef<TExtensionPoint>,
+    ref: ExtensionPoint<TExtensionPoint>,
     impl: TExtensionPoint,
   ): void;
   registerInit<Deps extends { [name in string]: unknown }>(options: {
-    deps: { [name in keyof Deps]: ServiceRef<Deps[name]> };
-    init: (deps: Deps) => Promise<void>;
+    deps: {
+      [name in keyof Deps]: ServiceRef<Deps[name]> | ExtensionPoint<Deps[name]>;
+    };
+    init(deps: Deps): Promise<void>;
   }): void;
 }
 
diff --git a/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts b/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts
index 279667560f..6b3f8e270f 100644
--- a/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts
+++ b/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts
@@ -19,12 +19,12 @@ import {
   createServiceFactory,
   createServiceRef,
 } from '@backstage/backend-plugin-api';
-import { createTestBackend, startTestBackend } from './TestBackend';
+import { startTestBackend } from './TestBackend';
 
 describe('TestBackend', () => {
   it('should get a type error if service implementation does not match', () => {
     const serviceRef = createServiceRef<{ a: string; b: string }>({ id: 'a' });
-    const backend = createTestBackend({
+    const backend = startTestBackend({
       services: [
         [serviceRef, { a: 'a' }],
         [serviceRef, { a: 'a', b: 'b' }],
@@ -68,7 +68,7 @@ describe('TestBackend', () => {
 
     await startTestBackend({
       services: [sf],
-      registrables: [testModule({})],
+      features: [testModule({})],
     });
 
     expect(testFn).toBeCalledWith('winning');
diff --git a/packages/backend-test-utils/src/next/wiring/TestBackend.ts b/packages/backend-test-utils/src/next/wiring/TestBackend.ts
index 150d4ce2af..b9276fa9b9 100644
--- a/packages/backend-test-utils/src/next/wiring/TestBackend.ts
+++ b/packages/backend-test-utils/src/next/wiring/TestBackend.ts
@@ -14,31 +14,54 @@
  * limitations under the License.
  */
 
-import { Backend, createSpecializedBackend } from '@backstage/backend-app-api';
+import { createSpecializedBackend } from '@backstage/backend-app-api';
 import {
   AnyServiceFactory,
   ServiceRef,
   createServiceFactory,
   BackendFeature,
+  ExtensionPoint,
 } from '@backstage/backend-plugin-api';
 
 /** @alpha */
-export interface TestBackendOptions<TServices extends any[]> {
-  services: readonly [
+export interface TestBackendOptions<
+  TServices extends any[],
+  TExtensionPoints extends any[],
+> {
+  services?: readonly [
     ...{
       [index in keyof TServices]:
         | AnyServiceFactory
         | [ServiceRef<TServices[index]>, Partial<TServices[index]>];
     },
   ];
+  extensionPoints?: readonly [
+    ...{
+      [index in keyof TExtensionPoints]: [
+        ExtensionPoint<TExtensionPoints[index]>,
+        Partial<TExtensionPoints[index]>,
+      ];
+    },
+  ];
+  features?: BackendFeature[];
 }
 
 /** @alpha */
-export function createTestBackend<TServices extends any[]>(
-  options: TestBackendOptions<TServices>,
-): Backend {
-  const factories = options.services?.map(serviceDef => {
+export async function startTestBackend<
+  TServices extends any[],
+  TExtensionPoints extends any[],
+>(options: TestBackendOptions<TServices, TExtensionPoints>): Promise<void> {
+  const {
+    services = [],
+    extensionPoints = [],
+    features = [],
+    ...otherOptions
+  } = options;
+
+  const factories = services.map(serviceDef => {
     if (Array.isArray(serviceDef)) {
+      // if type is ExtensionPoint?
+      // do something differently?
       return createServiceFactory({
         service: serviceDef[0],
         deps: {},
@@ -47,19 +70,26 @@ export function createTestBackend<TServices extends any[]>(
     }
     return serviceDef as AnyServiceFactory;
   });
-  return createSpecializedBackend({ services: factories ?? [] });
-}
 
-/** @alpha */
-export async function startTestBackend<TServices extends any[]>(
-  options: TestBackendOptions<TServices> & {
-    features?: BackendFeature[];
-  },
-): Promise<void> {
-  const { features = [], ...otherOptions } = options;
-  const backend = createTestBackend(otherOptions);
+  const backend = createSpecializedBackend({
+    ...otherOptions,
+    services: factories,
+  });
+
+  backend.add({
+    id: `---test-extension-point-registrar`,
+    register(reg) {
+      for (const [ref, impl] of extensionPoints) {
+        reg.registerExtensionPoint(ref, impl);
+      }
+
+      reg.registerInit({ deps: {}, async init() {} });
+    },
+  });
+
   for (const feature of features) {
     backend.add(feature);
   }
+
   await backend.start();
 }
diff --git a/packages/backend-test-utils/src/next/wiring/index.ts b/packages/backend-test-utils/src/next/wiring/index.ts
index 18a35c2b66..eb7b773e33 100644
--- a/packages/backend-test-utils/src/next/wiring/index.ts
+++ b/packages/backend-test-utils/src/next/wiring/index.ts
@@ -14,5 +14,5 @@
  * limitations under the License.
  */
 
-export { createTestBackend, startTestBackend } from './TestBackend';
+export { startTestBackend } from './TestBackend';
 export type { TestBackendOptions } from './TestBackend';
diff --git a/plugins/catalog-node/src/extensions.ts b/plugins/catalog-node/src/extensions.ts
index 9f76946d30..80fbd7630f 100644
--- a/plugins/catalog-node/src/extensions.ts
+++ b/plugins/catalog-node/src/extensions.ts
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { createServiceRef } from '@backstage/backend-plugin-api';
+import { createExtensionPoint } from '@backstage/backend-plugin-api';
 import { EntityProvider } from './api';
 import { CatalogProcessor } from './api/processor';
 
@@ -29,6 +29,6 @@ export interface CatalogProcessingExtensionPoint {
  * @alpha
  */
 export const catalogProcessingExtensionPoint =
-  createServiceRef<CatalogProcessingExtensionPoint>({
+  createExtensionPoint<CatalogProcessingExtensionPoint>({
     id: 'catalog.processing',
   });
diff --git a/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts b/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts
index a969d80a1b..e8ed3bf505 100644
--- a/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts
+++ b/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts
@@ -23,8 +23,9 @@ describe('ScaffolderCatalogModule', () => {
   it('should register the extension point', async () => {
     const extensionPoint = { addProcessor: jest.fn() };
     await startTestBackend({
-      services: [[catalogProcessingExtensionPoint, extensionPoint]],
-      registrables: [scaffolderCatalogModule({})],
+      services: [],
+      extensionPoints: [[catalogProcessingExtensionPoint, extensionPoint]],
+      features: [scaffolderCatalogModule({})],
     });
 
     expect(extensionPoint.addProcessor).toHaveBeenCalledWith(

From 3f37ff4c42a90a403e05524d0027513743d75bf9 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 15:32:25 +0200
Subject: [PATCH 5/9] chore: remove unused parameter

Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../src/extension/ScaffolderCatalogModule.test.ts                | 1 -
 1 file changed, 1 deletion(-)

diff --git a/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts b/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts
index e8ed3bf505..1ced3dd676 100644
--- a/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts
+++ b/plugins/scaffolder-backend/src/extension/ScaffolderCatalogModule.test.ts
@@ -23,7 +23,6 @@ describe('ScaffolderCatalogModule', () => {
   it('should register the extension point', async () => {
     const extensionPoint = { addProcessor: jest.fn() };
     await startTestBackend({
-      services: [],
       extensionPoints: [[catalogProcessingExtensionPoint, extensionPoint]],
       features: [scaffolderCatalogModule({})],
     });

From 0599732ec0dd8b392f525ce24ababa38da541945 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 15:40:23 +0200
Subject: [PATCH 6/9] add changeset

Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .changeset/cyan-pens-suffer.md | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 .changeset/cyan-pens-suffer.md

diff --git a/.changeset/cyan-pens-suffer.md b/.changeset/cyan-pens-suffer.md
new file mode 100644
index 0000000000..b7d3a3a096
--- /dev/null
+++ b/.changeset/cyan-pens-suffer.md
@@ -0,0 +1,8 @@
+---
+'@backstage/backend-app-api': patch
+'@backstage/backend-plugin-api': patch
+'@backstage/backend-test-utils': patch
+'@backstage/plugin-catalog-node': patch
+---
+
+Refactored experimental backend system with new type names.

From c2e7491890a6ac0deb360e90e6c075f77fdee659 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 15:58:36 +0200
Subject: [PATCH 7/9] backend-app-api: Improve error handling
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>
Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../src/wiring/BackendInitializer.ts          | 47 ++++++++++++-------
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/packages/backend-app-api/src/wiring/BackendInitializer.ts b/packages/backend-app-api/src/wiring/BackendInitializer.ts
index c1b7089827..afb5250504 100644
--- a/packages/backend-app-api/src/wiring/BackendInitializer.ts
+++ b/packages/backend-app-api/src/wiring/BackendInitializer.ts
@@ -40,17 +40,35 @@ export class BackendInitializer {
     deps: { [name: string]: ServiceOrExtensionPoint },
     pluginId: string,
   ) {
-    return Object.fromEntries(
-      await Promise.all(
-        Object.entries(deps).map(async ([name, ref]) => [
-          name,
-          this.#extensionPoints.get(ref as ExtensionPoint<unknown>) ||
-            (await this.#serviceHolder.get(ref as ServiceRef<unknown>)!(
-              pluginId,
-            )),
-        ]),
-      ),
-    );
+    const result = new Map<string, unknown>();
+    const missingRefs = new Set<ServiceOrExtensionPoint>();
+
+    for (const [name, ref] of Object.entries(deps)) {
+      const extensionPoint = this.#extensionPoints.get(
+        ref as ExtensionPoint<unknown>,
+      );
+      if (extensionPoint) {
+        result.set(name, extensionPoint);
+      } else {
+        const factory = await this.#serviceHolder.get(
+          ref as ServiceRef<unknown>,
+        );
+        if (factory) {
+          result.set(name, await factory(pluginId));
+        } else {
+          missingRefs.add(ref);
+        }
+      }
+    }
+
+    if (missingRefs.size > 0) {
+      const missing = Array.from(missingRefs).join(', ');
+      throw new Error(
+        `No extension point or service available for the following ref(s): ${missing}`,
+      );
+    }
+
+    return Object.fromEntries(result);
   }
 
   add<TOptions>(feature: BackendFeature, options?: TOptions) {
@@ -61,7 +79,6 @@ export class BackendInitializer {
   }
 
   async start(): Promise<void> {
-    console.log(`Starting backend`);
     if (this.#started) {
       throw new Error('Backend has already started');
     }
@@ -72,7 +89,6 @@ export class BackendInitializer {
 
       let registerInit: BackendRegisterInit | undefined = undefined;
 
-      console.log('Registering', feature.id);
       feature.register({
         registerExtensionPoint: (extensionPointRef, impl) => {
           if (registerInit) {
@@ -107,8 +123,6 @@ export class BackendInitializer {
       this.#registerInits.push(registerInit);
     }
 
-    this.validateSetup();
-
     const orderedRegisterResults = this.#resolveInitOrder(this.#registerInits);
 
     for (const registerInit of orderedRegisterResults) {
@@ -117,8 +131,6 @@ export class BackendInitializer {
     }
   }
 
-  private validateSetup() {}
-
   #resolveInitOrder(registerInits: Array<BackendRegisterInit>) {
     let registerInitsToOrder = registerInits.slice();
     const orderedRegisterInits = new Array<BackendRegisterInit>();
@@ -142,7 +154,6 @@ export class BackendInitializer {
         }
 
         if (unInitializedDependents.length === 0) {
-          console.log(`DEBUG: pushed ${registerInit.id} to results`);
           orderedRegisterInits.push(registerInit);
           toRemove.add(registerInit);
         }

From b76eeaf302b691705ba9737d59e36aa3f87efc6a Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 15:58:52 +0200
Subject: [PATCH 8/9] add api reports

Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 packages/backend-app-api/api-report.md    | 11 +++++-
 packages/backend-plugin-api/api-report.md | 48 +++++++++++------------
 packages/backend-test-utils/api-report.md | 36 ++++++++++-------
 plugins/catalog-backend/api-report.md     |  4 +-
 plugins/catalog-node/api-report.md        |  4 +-
 plugins/scaffolder-backend/api-report.md  |  4 +-
 6 files changed, 61 insertions(+), 46 deletions(-)

diff --git a/packages/backend-app-api/api-report.md b/packages/backend-app-api/api-report.md
index 130ad6d1f1..26c8179771 100644
--- a/packages/backend-app-api/api-report.md
+++ b/packages/backend-app-api/api-report.md
@@ -4,8 +4,9 @@
 
 ```ts
 import { AnyServiceFactory } from '@backstage/backend-plugin-api';
-import { BackendRegistrable } from '@backstage/backend-plugin-api';
+import { BackendFeature } from '@backstage/backend-plugin-api';
 import { Config } from '@backstage/config';
+import { ExtensionPoint } from '@backstage/backend-plugin-api';
 import { HttpRouterService } from '@backstage/backend-plugin-api';
 import { Logger } from '@backstage/backend-plugin-api';
 import { PermissionAuthorizer } from '@backstage/plugin-permission-common';
@@ -15,13 +16,14 @@ import { PluginDatabaseManager } from '@backstage/backend-common';
 import { PluginEndpointDiscovery } from '@backstage/backend-common';
 import { PluginTaskScheduler } from '@backstage/backend-tasks';
 import { ServiceFactory } from '@backstage/backend-plugin-api';
+import { ServiceRef } from '@backstage/backend-plugin-api';
 import { TokenManager } from '@backstage/backend-common';
 import { UrlReader } from '@backstage/backend-common';
 
 // @public (undocumented)
 export interface Backend {
   // (undocumented)
-  add(extension: BackendRegistrable): void;
+  add(feature: BackendFeature): void;
   // (undocumented)
   start(): Promise<void>;
 }
@@ -85,6 +87,11 @@ export const schedulerFactory: ServiceFactory<
   {}
 >;
 
+// @public (undocumented)
+export type ServiceOrExtensionPoint<T = unknown> =
+  | ExtensionPoint<T>
+  | ServiceRef<T>;
+
 // @public (undocumented)
 export const tokenManagerFactory: ServiceFactory<
   TokenManager,
diff --git a/packages/backend-plugin-api/api-report.md b/packages/backend-plugin-api/api-report.md
index 44791f5744..fa5097be64 100644
--- a/packages/backend-plugin-api/api-report.md
+++ b/packages/backend-plugin-api/api-report.md
@@ -26,23 +26,11 @@ export type AnyServiceFactory = ServiceFactory<
 >;
 
 // @public (undocumented)
-export interface BackendInitRegistry {
+export interface BackendFeature {
   // (undocumented)
-  registerExtensionPoint<TExtensionPoint>(
-    ref: ServiceRef<TExtensionPoint>,
-    impl: TExtensionPoint,
-  ): void;
+  id: string;
   // (undocumented)
-  registerInit<
-    Deps extends {
-      [name in string]: unknown;
-    },
-  >(options: {
-    deps: {
-      [name in keyof Deps]: ServiceRef<Deps[name]>;
-    };
-    init: (deps: Deps) => Promise<void>;
-  }): void;
+  register(reg: BackendRegistrationPoints): void;
 }
 
 // @public (undocumented)
@@ -53,7 +41,7 @@ export interface BackendModuleConfig<TOptions> {
   pluginId: string;
   // (undocumented)
   register(
-    reg: Omit<BackendInitRegistry, 'registerExtensionPoint'>,
+    reg: Omit<BackendRegistrationPoints, 'registerExtensionPoint'>,
     options: TOptions,
   ): void;
 }
@@ -63,15 +51,27 @@ export interface BackendPluginConfig<TOptions> {
   // (undocumented)
   id: string;
   // (undocumented)
-  register(reg: BackendInitRegistry, options: TOptions): void;
+  register(reg: BackendRegistrationPoints, options: TOptions): void;
 }
 
 // @public (undocumented)
-export interface BackendRegistrable {
+export interface BackendRegistrationPoints {
   // (undocumented)
-  id: string;
+  registerExtensionPoint<TExtensionPoint>(
+    ref: ExtensionPoint<TExtensionPoint>,
+    impl: TExtensionPoint,
+  ): void;
   // (undocumented)
-  register(reg: BackendInitRegistry): void;
+  registerInit<
+    Deps extends {
+      [name in string]: unknown;
+    },
+  >(options: {
+    deps: {
+      [name in keyof Deps]: ServiceRef<Deps[name]> | ExtensionPoint<Deps[name]>;
+    };
+    init(deps: Deps): Promise<void>;
+  }): void;
 }
 
 // @public (undocumented)
@@ -84,15 +84,15 @@ export const configServiceRef: ServiceRef<Config>;
 export function createBackendModule<TOptions>(
   config: BackendModuleConfig<TOptions>,
 ): undefined extends TOptions
-  ? (options?: TOptions) => BackendRegistrable
-  : (options: TOptions) => BackendRegistrable;
+  ? (options?: TOptions) => BackendFeature
+  : (options: TOptions) => BackendFeature;
 
 // @public (undocumented)
 export function createBackendPlugin<TOptions>(
   config: BackendPluginConfig<TOptions>,
 ): undefined extends TOptions
-  ? (options?: TOptions) => BackendRegistrable
-  : (options: TOptions) => BackendRegistrable;
+  ? (options?: TOptions) => BackendFeature
+  : (options: TOptions) => BackendFeature;
 
 // @public (undocumented)
 export function createExtensionPoint<T>(options: {
diff --git a/packages/backend-test-utils/api-report.md b/packages/backend-test-utils/api-report.md
index 9c75402b43..b8881e659d 100644
--- a/packages/backend-test-utils/api-report.md
+++ b/packages/backend-test-utils/api-report.md
@@ -4,16 +4,11 @@
 
 ```ts
 import { AnyServiceFactory } from '@backstage/backend-plugin-api';
-import { Backend } from '@backstage/backend-app-api';
-import { BackendRegistrable } from '@backstage/backend-plugin-api';
+import { BackendFeature } from '@backstage/backend-plugin-api';
+import { ExtensionPoint } from '@backstage/backend-plugin-api';
 import { Knex } from 'knex';
 import { ServiceRef } from '@backstage/backend-plugin-api';
 
-// @alpha (undocumented)
-export function createTestBackend<TServices extends any[]>(
-  options: TestBackendOptions<TServices>,
-): Backend;
-
 // @public (undocumented)
 export function isDockerDisabledForTests(): boolean;
 
@@ -25,16 +20,29 @@ export function setupRequestMockHandlers(worker: {
 }): void;
 
 // @alpha (undocumented)
-export function startTestBackend<TServices extends any[]>(
-  options: TestBackendOptions<TServices> & {
-    registrables?: BackendRegistrable[];
-  },
-): Promise<void>;
+export function startTestBackend<
+  TServices extends any[],
+  TExtensionPoints extends any[],
+>(options: TestBackendOptions<TServices, TExtensionPoints>): Promise<void>;
 
 // @alpha (undocumented)
-export interface TestBackendOptions<TServices extends any[]> {
+export interface TestBackendOptions<
+  TServices extends any[],
+  TExtensionPoints extends any[],
+> {
   // (undocumented)
-  services: readonly [
+  extensionPoints?: readonly [
+    ...{
+      [index in keyof TExtensionPoints]: [
+        ExtensionPoint<TExtensionPoints[index]>,
+        Partial<TExtensionPoints[index]>,
+      ];
+    },
+  ];
+  // (undocumented)
+  features?: BackendFeature[];
+  // (undocumented)
+  services?: readonly [
     ...{
       [index in keyof TServices]:
         | AnyServiceFactory
diff --git a/plugins/catalog-backend/api-report.md b/plugins/catalog-backend/api-report.md
index fa6806933d..55f2d114db 100644
--- a/plugins/catalog-backend/api-report.md
+++ b/plugins/catalog-backend/api-report.md
@@ -5,7 +5,7 @@
 ```ts
 /// <reference types="node" />
 
-import { BackendRegistrable } from '@backstage/backend-plugin-api';
+import { BackendFeature } from '@backstage/backend-plugin-api';
 import { CatalogApi } from '@backstage/catalog-client';
 import { CatalogEntityDocument } from '@backstage/plugin-catalog-common';
 import { CatalogProcessor } from '@backstage/plugin-catalog-node';
@@ -224,7 +224,7 @@ export type CatalogPermissionRule<TParams extends unknown[] = unknown[]> =
   PermissionRule<Entity, EntitiesSearchFilter, 'catalog-entity', TParams>;
 
 // @alpha
-export const catalogPlugin: (options?: unknown) => BackendRegistrable;
+export const catalogPlugin: (options?: unknown) => BackendFeature;
 
 // @public (undocumented)
 export interface CatalogProcessingEngine {
diff --git a/plugins/catalog-node/api-report.md b/plugins/catalog-node/api-report.md
index 47a9bdf45c..46e3efef99 100644
--- a/plugins/catalog-node/api-report.md
+++ b/plugins/catalog-node/api-report.md
@@ -7,8 +7,8 @@
 
 import { CompoundEntityRef } from '@backstage/catalog-model';
 import { Entity } from '@backstage/catalog-model';
+import { ExtensionPoint } from '@backstage/backend-plugin-api';
 import { JsonValue } from '@backstage/types';
-import { ServiceRef } from '@backstage/backend-plugin-api';
 
 // @alpha (undocumented)
 export interface CatalogProcessingExtensionPoint {
@@ -19,7 +19,7 @@ export interface CatalogProcessingExtensionPoint {
 }
 
 // @alpha (undocumented)
-export const catalogProcessingExtensionPoint: ServiceRef<CatalogProcessingExtensionPoint>;
+export const catalogProcessingExtensionPoint: ExtensionPoint<CatalogProcessingExtensionPoint>;
 
 // @public (undocumented)
 export type CatalogProcessor = {
diff --git a/plugins/scaffolder-backend/api-report.md b/plugins/scaffolder-backend/api-report.md
index 6e7220964d..96a4d7b400 100644
--- a/plugins/scaffolder-backend/api-report.md
+++ b/plugins/scaffolder-backend/api-report.md
@@ -5,7 +5,7 @@
 ```ts
 /// <reference types="node" />
 
-import { BackendRegistrable } from '@backstage/backend-plugin-api';
+import { BackendFeature } from '@backstage/backend-plugin-api';
 import { CatalogApi } from '@backstage/catalog-client';
 import { CatalogProcessor } from '@backstage/plugin-catalog-backend';
 import { CatalogProcessorEmit } from '@backstage/plugin-catalog-backend';
@@ -566,7 +566,7 @@ export type RunCommandOptions = {
 };
 
 // @alpha
-export const scaffolderCatalogModule: (options?: unknown) => BackendRegistrable;
+export const scaffolderCatalogModule: (options?: unknown) => BackendFeature;
 
 // @public (undocumented)
 export class ScaffolderEntitiesProcessor implements CatalogProcessor {

From 91dd47a6a182641d880b265244f8f2e2114a87a1 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Fri, 12 Aug 2022 16:09:17 +0200
Subject: [PATCH 9/9] chore: update backend tests
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>
Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../src/next/wiring/TestBackend.test.ts       | 29 ++++++++++++++++---
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts b/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts
index 6b3f8e270f..488a258388 100644
--- a/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts
+++ b/packages/backend-test-utils/src/next/wiring/TestBackend.test.ts
@@ -16,16 +16,25 @@
 
 import {
   createBackendModule,
+  createExtensionPoint,
   createServiceFactory,
   createServiceRef,
 } from '@backstage/backend-plugin-api';
 import { startTestBackend } from './TestBackend';
 
 describe('TestBackend', () => {
-  it('should get a type error if service implementation does not match', () => {
-    const serviceRef = createServiceRef<{ a: string; b: string }>({ id: 'a' });
-    const backend = startTestBackend({
+  it('should get a type error if service implementation does not match', async () => {
+    type Obj = { a: string; b: string };
+    const serviceRef = createServiceRef<Obj>({ id: 'a' });
+    const extensionPoint1 = createExtensionPoint<Obj>({ id: 'b1' });
+    const extensionPoint2 = createExtensionPoint<Obj>({ id: 'b2' });
+    const extensionPoint3 = createExtensionPoint<Obj>({ id: 'b3' });
+    const extensionPoint4 = createExtensionPoint<Obj>({ id: 'b4' });
+    const extensionPoint5 = createExtensionPoint<Obj>({ id: 'b5' });
+    await startTestBackend({
       services: [
+        // @ts-expect-error
+        [extensionPoint1, { a: 'a' }],
         [serviceRef, { a: 'a' }],
         [serviceRef, { a: 'a', b: 'b' }],
         // @ts-expect-error
@@ -35,8 +44,20 @@ describe('TestBackend', () => {
         // @ts-expect-error
         [serviceRef, { a: 'a', b: 'b', c: 'c' }],
       ],
+      extensionPoints: [
+        // @ts-expect-error
+        [serviceRef, { a: 'a' }],
+        [extensionPoint1, { a: 'a' }],
+        [extensionPoint2, { a: 'a', b: 'b' }],
+        // @ts-expect-error
+        [extensionPoint3, { c: 'c' }],
+        // @ts-expect-error
+        [extensionPoint4, { a: 'a', c: 'c' }],
+        // @ts-expect-error
+        [extensionPoint5, { a: 'a', b: 'b', c: 'c' }],
+      ],
     });
-    expect(backend).toBeDefined();
+    expect(1).toBe(1);
   });
 
   it('should start the test backend', async () => {