backend-app-api: switch out http router pathPrefix option for getPath + tests

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/fair-ants-work.md

@@ -2,6 +2,6 @@
 '@backstage/backend-app-api': minor
 ---
 
-**BREAKING**: The `httpRouterFactory` now accepts a `pathPrefix` option rather than `indexPlugin`. To set up custom index path, configure the new `rootHttpRouterFactory` with a custom `indexPath` instead.
+**BREAKING**: The `httpRouterFactory` now accepts a `getPath` option rather than `indexPlugin`. To set up custom index path, configure the new `rootHttpRouterFactory` with a custom `indexPath` instead.
 
 Added an implementation for the new `rootHttpRouterServiceRef`.

packages/backend-app-api/api-report.md

@@ -71,7 +71,7 @@ export const httpRouterFactory: (
 
 // @public (undocumented)
 export type HttpRouterFactoryOptions = {
-  pathPrefix?: string;
+  getPath(pluginId: string): string;
 };
 
 // @public

packages/backend-app-api/src/services/implementations/httpRouterService.test.ts

@@ -0,0 +1,70 @@
+/*
+ * 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 {
+  HttpRouterService,
+  ServiceFactory,
+} from '@backstage/backend-plugin-api';
+import { httpRouterFactory } from './httpRouterService';
+
+describe('httpRouterFactory', () => {
+  it('should register plugin paths', async () => {
+    const rootHttpRouter = { use: jest.fn() };
+    const factory = httpRouterFactory() as Exclude<
+      ServiceFactory<HttpRouterService>,
+      { scope: 'root' }
+    >;
+    const innerFactory = await factory.factory({ rootHttpRouter });
+
+    const handler1 = () => {};
+    const router1 = await innerFactory({ plugin: { getId: () => 'test1' } });
+    router1.use(handler1);
+    expect(rootHttpRouter.use).toHaveBeenCalledTimes(1);
+    expect(rootHttpRouter.use).toHaveBeenCalledWith('/api/test1', handler1);
+
+    const handler2 = () => {};
+    const router2 = await innerFactory({ plugin: { getId: () => 'test2' } });
+    router2.use(handler2);
+    expect(rootHttpRouter.use).toHaveBeenCalledTimes(2);
+    expect(rootHttpRouter.use).toHaveBeenCalledWith('/api/test2', handler2);
+  });
+
+  it('should use custom path generator', async () => {
+    const rootHttpRouter = { use: jest.fn() };
+    const factory = httpRouterFactory({
+      getPath: id => `/some/${id}/path`,
+    }) as Exclude<ServiceFactory<HttpRouterService>, { scope: 'root' }>;
+    const innerFactory = await factory.factory({ rootHttpRouter });
+
+    const handler1 = () => {};
+    const router1 = await innerFactory({ plugin: { getId: () => 'test1' } });
+    router1.use(handler1);
+    expect(rootHttpRouter.use).toHaveBeenCalledTimes(1);
+    expect(rootHttpRouter.use).toHaveBeenCalledWith(
+      '/some/test1/path',
+      handler1,
+    );
+
+    const handler2 = () => {};
+    const router2 = await innerFactory({ plugin: { getId: () => 'test2' } });
+    router2.use(handler2);
+    expect(rootHttpRouter.use).toHaveBeenCalledTimes(2);
+    expect(rootHttpRouter.use).toHaveBeenCalledWith(
+      '/some/test2/path',
+      handler2,
+    );
+  });
+});

packages/backend-app-api/src/services/implementations/httpRouterService.ts

@@ -25,9 +25,9 @@ import { Handler } from 'express';
  */
 export type HttpRouterFactoryOptions = {
   /**
-   * The path prefix used for each plugin, defaults to `/api/`.
+   * A callback used to generate the path for each plugin, defaults to `/api/{pluginId}`.
    */
-  pathPrefix?: string;
+  getPath(pluginId: string): string;
 };
 
 /** @public */
@@ -38,10 +38,10 @@ export const httpRouterFactory = createServiceFactory({
     rootHttpRouter: coreServices.rootHttpRouter,
   },
   async factory({ rootHttpRouter }, options?: HttpRouterFactoryOptions) {
-    const pathPrefix = options?.pathPrefix ?? '/api/';
+    const getPath = options?.getPath ?? (id => `/api/${id}`);
 
     return async ({ plugin }) => {
-      const path = pathPrefix + plugin.getId();
+      const path = getPath(plugin.getId());
       return {
         use(handler: Handler) {
           rootHttpRouter.use(path, handler);