fix(service-worker): correctly serve ngsw/state with a non-root SW scope (#37922)

The Angular ServiceWorker can serve requests to a special virtual path,
`ngsw/state`, showing [information about its internal state][1], which
can be useful for debugging.

Previously, this would only work if the ServiceWorker's [scope][2] was
the root directory (`/`). Otherwise, (e.g. when building the app with
`--baseHref=/some/path/`), the ServiceWorker would fail to detect a
request to `/some/path/ngsw/state` as matching `ngsw/state` and would
not serve it with the debugging information.

This commit fixes it by ensuring that the ServiceWorker's scope is taken
into account when detecting a request to `ngsw/state`.

[1]: https://angular.io/guide/service-worker-devops#locating-and-analyzing-debugging-information
[2]: https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerRegistration/scope

Fixes #30505

PR Close #37922

packages/service-worker/worker/src/driver.ts

@@ -99,6 +99,8 @@ export class Driver implements Debuggable, UpdateSource {
    */
   private loggedInvalidOnlyIfCachedRequest: boolean = false;
 
+  private ngswStatePath = this.adapter.parseUrl('ngsw/state', this.scope.registration.scope).path;
+
   /**
    * A scheduler which manages a queue of tasks that need to be executed when the SW is
    * not doing any other work (not processing any other requests).
@@ -184,7 +186,7 @@ export class Driver implements Debuggable, UpdateSource {
     }
 
     // The only thing that is served unconditionally is the debug page.
-    if (requestUrlObj.path === '/ngsw/state') {
+    if (requestUrlObj.path === this.ngswStatePath) {
       // Allow the debugger to handle the request, but don't affect SW state in any other way.
       event.respondWith(this.debugger.handleFetch(req));
       return;

packages/service-worker/worker/test/happy_spec.ts

@@ -893,6 +893,34 @@ describe('Driver', () => {
        expect(await scope.caches.keys()).not.toEqual([]);
      });
 
+  describe('serving ngsw/state', () => {
+    it('should show debug info (when in NORMAL state)', async () => {
+      expect(await makeRequest(scope, '/ngsw/state'))
+          .toMatch(/^NGSW Debug Info:\n\nDriver state: NORMAL/);
+    });
+
+    it('should show debug info (when in EXISTING_CLIENTS_ONLY state)', async () => {
+      driver.state = DriverReadyState.EXISTING_CLIENTS_ONLY;
+      expect(await makeRequest(scope, '/ngsw/state'))
+          .toMatch(/^NGSW Debug Info:\n\nDriver state: EXISTING_CLIENTS_ONLY/);
+    });
+
+    it('should show debug info (when in SAFE_MODE state)', async () => {
+      driver.state = DriverReadyState.SAFE_MODE;
+      expect(await makeRequest(scope, '/ngsw/state'))
+          .toMatch(/^NGSW Debug Info:\n\nDriver state: SAFE_MODE/);
+    });
+
+    it('should show debug info when the scope is not root', async () => {
+      const newScope =
+          new SwTestHarnessBuilder('http://localhost/foo/bar/').withServerState(server).build();
+      new Driver(newScope, newScope, new CacheDatabase(newScope, newScope));
+
+      expect(await makeRequest(newScope, '/foo/bar/ngsw/state'))
+          .toMatch(/^NGSW Debug Info:\n\nDriver state: NORMAL/);
+    });
+  });
+
   describe('cache naming', () => {
     // Helpers
     const cacheKeysFor = (baseHref: string) =>