backend-test-utils: add update method for mockServices.rootConfig

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

.changeset/giant-zebras-peel.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-test-utils': minor
+---
+
+The `mockServices.rootConfig()` instance now has an `update` method that can be used to test configuration subscriptions and updates.

packages/backend-test-utils/package.json

@@ -71,6 +71,7 @@
     "fs-extra": "^11.0.0",
     "keyv": "^5.2.1",
     "knex": "^3.0.0",
+    "lodash": "^4.17.21",
     "mysql2": "^3.0.0",
     "pg": "^8.11.3",
     "pg-connection-string": "^2.3.0",
@@ -84,6 +85,7 @@
   "devDependencies": {
     "@backstage/cli": "workspace:^",
     "@types/jest": "*",
+    "@types/lodash": "^4.14.151",
     "@types/supertest": "^2.0.8",
     "supertest": "^7.0.0"
   }

packages/backend-test-utils/report.api.md

@@ -305,7 +305,11 @@ export namespace mockServices {
       ) => ServiceMock<PermissionsRegistryService>;
   }
   // (undocumented)
-  export function rootConfig(options?: rootConfig.Options): RootConfigService;
+  export function rootConfig(
+    options?: rootConfig.Options,
+  ): RootConfigService & {
+    update(options: { data: JsonObject }): void;
+  };
   // (undocumented)
   export namespace rootConfig {
     // (undocumented)

packages/backend-test-utils/src/services/mockServices.test.ts

@@ -30,3 +30,37 @@ describe('mockServices', () => {
     expect(mockServices[key].factory()).toEqual(expect.any(Object));
   });
 });
+
+describe('mockServices.rootConfig()', () => {
+  it('should notify about updates', async () => {
+    const config = mockServices.rootConfig();
+
+    const fooConfig = config.getConfig('foo');
+
+    const rootListener = jest.fn();
+    const fooListener = jest.fn();
+
+    config.subscribe?.(rootListener);
+    fooConfig.subscribe?.(fooListener);
+
+    expect(rootListener).toHaveBeenCalledTimes(0);
+    expect(fooListener).toHaveBeenCalledTimes(0);
+
+    config.update({ data: { foo: { bar: 1, baz: 2 } } });
+
+    expect(rootListener).toHaveBeenCalledTimes(1);
+    expect(fooListener).toHaveBeenCalledTimes(1);
+
+    config.update({ data: { foo: { baz: 2, bar: 1 } } });
+
+    // Doesn't notify, no changes
+    expect(rootListener).toHaveBeenCalledTimes(1);
+    expect(fooListener).toHaveBeenCalledTimes(1);
+
+    config.update({ data: { foo: { bar: 1, baz: 2 }, unrelated: 'key' } });
+
+    // Notifies all listeners, even if an unrelated key was changed
+    expect(rootListener).toHaveBeenCalledTimes(2);
+    expect(fooListener).toHaveBeenCalledTimes(2);
+  });
+});

packages/backend-test-utils/src/services/mockServices.ts

@@ -58,6 +58,8 @@ import { MockEventsService } from './MockEventsService';
 import { MockPermissionsService } from './MockPermissionsService';
 import { simpleMock } from './simpleMock';
 import { MockSchedulerService } from './MockSchedulerService';
+// eslint-disable-next-line @backstage/no-relative-monorepo-imports
+import { ObservableConfigProxy } from '../../../config-loader/src/sources/ObservableConfigProxy';
 
 /** @internal */
 function createLoggerMock() {
@@ -137,8 +139,16 @@ function simpleFactoryWithOptions<
  * ```
  */
 export namespace mockServices {
-  export function rootConfig(options?: rootConfig.Options): RootConfigService {
-    return new ConfigReader(options?.data, 'mock-config');
+  export function rootConfig(
+    options?: rootConfig.Options,
+  ): RootConfigService & { update(options: { data: JsonObject }): void } {
+    const config = ObservableConfigProxy.create(new AbortController());
+    config.setConfig(new ConfigReader(options?.data ?? {}, 'mock-config'));
+    return Object.assign(config, {
+      update({ data }: { data: JsonObject }): void {
+        config.setConfig(new ConfigReader(data, 'mock-config'));
+      },
+    });
   }
   export namespace rootConfig {
     export type Options = { data?: JsonObject };

yarn.lock

@@ -2755,6 +2755,7 @@ __metadata:
     "@types/express-serve-static-core": "npm:^4.17.5"
     "@types/jest": "npm:*"
     "@types/keyv": "npm:^4.2.0"
+    "@types/lodash": "npm:^4.14.151"
     "@types/qs": "npm:^6.9.6"
     "@types/supertest": "npm:^2.0.8"
     better-sqlite3: "npm:^12.0.0"
@@ -2763,6 +2764,7 @@ __metadata:
     fs-extra: "npm:^11.0.0"
     keyv: "npm:^5.2.1"
     knex: "npm:^3.0.0"
+    lodash: "npm:^4.17.21"
     mysql2: "npm:^3.0.0"
     pg: "npm:^8.11.3"
     pg-connection-string: "npm:^2.3.0"