Ensure http interceptors are shares across lifecycle methods (#57150)

src/core/public/core_system.ts

@@ -211,7 +211,7 @@ export class CoreSystem {
       const injectedMetadata = await this.injectedMetadata.start();
       const uiSettings = await this.uiSettings.start();
       const docLinks = await this.docLinks.start({ injectedMetadata });
-      const http = await this.http.start({ injectedMetadata, fatalErrors: this.fatalErrorsSetup! });
+      const http = await this.http.start();
       const savedObjects = await this.savedObjects.start({ http });
       const i18n = await this.i18n.start();
       const fatalErrors = await this.fatalErrors.start();

src/core/public/http/http_service.test.ts

@@ -25,13 +25,40 @@ import { fatalErrorsServiceMock } from '../fatal_errors/fatal_errors_service.moc
 import { injectedMetadataServiceMock } from '../injected_metadata/injected_metadata_service.mock';
 import { HttpService } from './http_service';
 
+describe('interceptors', () => {
+  afterEach(() => fetchMock.restore());
+
+  it('shares interceptors across setup and start', async () => {
+    fetchMock.get('*', {});
+    const injectedMetadata = injectedMetadataServiceMock.createSetupContract();
+    const fatalErrors = fatalErrorsServiceMock.createSetupContract();
+    const httpService = new HttpService();
+
+    const setup = httpService.setup({ fatalErrors, injectedMetadata });
+    const setupInterceptor = jest.fn();
+    setup.intercept({ request: setupInterceptor });
+
+    const start = httpService.start();
+    const startInterceptor = jest.fn();
+    start.intercept({ request: startInterceptor });
+
+    await setup.get('/blah');
+    expect(setupInterceptor).toHaveBeenCalledTimes(1);
+    expect(startInterceptor).toHaveBeenCalledTimes(1);
+
+    await start.get('/other-blah');
+    expect(setupInterceptor).toHaveBeenCalledTimes(2);
+    expect(startInterceptor).toHaveBeenCalledTimes(2);
+  });
+});
+
 describe('#stop()', () => {
   it('calls loadingCount.stop()', () => {
     const injectedMetadata = injectedMetadataServiceMock.createSetupContract();
     const fatalErrors = fatalErrorsServiceMock.createSetupContract();
     const httpService = new HttpService();
     httpService.setup({ fatalErrors, injectedMetadata });
-    httpService.start({ fatalErrors, injectedMetadata });
+    httpService.start();
     httpService.stop();
     expect(loadingServiceMock.stop).toHaveBeenCalled();
   });

src/core/public/http/http_service.ts

@@ -35,14 +35,15 @@ interface HttpDeps {
 export class HttpService implements CoreService<HttpSetup, HttpStart> {
   private readonly anonymousPaths = new AnonymousPathsService();
   private readonly loadingCount = new LoadingCountService();
+  private service?: HttpSetup;
 
   public setup({ injectedMetadata, fatalErrors }: HttpDeps): HttpSetup {
     const kibanaVersion = injectedMetadata.getKibanaVersion();
     const basePath = new BasePath(injectedMetadata.getBasePath());
     const fetchService = new Fetch({ basePath, kibanaVersion });
     const loadingCount = this.loadingCount.setup({ fatalErrors });
 
-    return {
+    this.service = {
       basePath,
       anonymousPaths: this.anonymousPaths.setup({ basePath }),
       intercept: fetchService.intercept.bind(fetchService),
@@ -56,10 +57,16 @@ export class HttpService implements CoreService<HttpSetup, HttpStart> {
       put: fetchService.put.bind(fetchService),
       ...loadingCount,
     };
+
+    return this.service;
   }
 
-  public start(deps: HttpDeps) {
-    return this.setup(deps);
+  public start() {
+    if (!this.service) {
+      throw new Error(`HttpService#setup() must be called first!`);
+    }
+
+    return this.service;
   }
 
   public stop() {