Chore: Replace deprecated toPromise() calls with lastValueFrom (#54234)

public/app/plugins/datasource/tempo/datasource.test.ts

@@ -30,10 +30,15 @@ import {
 import mockJson from './mockJsonResponse.json';
 import mockServiceGraph from './mockServiceGraph.json';
 
+let mockObservable: () => Observable<any>;
 jest.mock('@grafana/runtime', () => {
   return {
     ...jest.requireActual('@grafana/runtime'),
     reportInteraction: jest.fn(),
+    getBackendSrv: () => ({
+      fetch: mockObservable,
+      _request: mockObservable,
+    }),
   };
 });
 
@@ -343,6 +348,24 @@ describe('Tempo data source', () => {
     const lokiDS4 = ds4.getLokiSearchDS();
     expect(lokiDS4).toBe(undefined);
   });
+
+  describe('test the testDatasource function', () => {
+    it('should return a success msg if response.ok is true', async () => {
+      mockObservable = () => of({ ok: true });
+      const ds = new TempoDatasource(defaultSettings);
+      const response = await ds.testDatasource();
+      expect(response.status).toBe('success');
+    });
+  });
+
+  describe('test the metadataRequest function', () => {
+    it('should return the last value from the observed stream', async () => {
+      mockObservable = () => of('321', '123', '456');
+      const ds = new TempoDatasource(defaultSettings);
+      const response = await ds.metadataRequest('/api/search/tags');
+      expect(response).toBe('456');
+    });
+  });
 });
 
 describe('Tempo apm table', () => {

public/app/plugins/datasource/tempo/datasource.ts

@@ -1,5 +1,5 @@
 import { identity, pick, pickBy, groupBy, startCase } from 'lodash';
-import { EMPTY, from, merge, Observable, of, throwError } from 'rxjs';
+import { EMPTY, from, lastValueFrom, merge, Observable, of, throwError } from 'rxjs';
 import { catchError, concatMap, map, mergeMap, toArray } from 'rxjs/operators';
 
 import {
@@ -336,7 +336,7 @@ export class TempoDatasource extends DataSourceWithBackend<TempoQuery, TempoJson
   }
 
   async metadataRequest(url: string, params = {}) {
-    return await this._request(url, params, { method: 'GET', hideFromInspector: true }).toPromise();
+    return await lastValueFrom(this._request(url, params, { method: 'GET', hideFromInspector: true }));
   }
 
   private _request(apiUrl: string, data?: any, options?: Partial<BackendSrvRequest>): Observable<Record<string, any>> {
@@ -353,7 +353,7 @@ export class TempoDatasource extends DataSourceWithBackend<TempoQuery, TempoJson
       method: 'GET',
       url: `${this.instanceSettings.url}/api/echo`,
     };
-    const response = await getBackendSrv().fetch<any>(options).toPromise();
+    const response = await lastValueFrom(getBackendSrv().fetch<any>(options));
 
     if (response?.ok) {
       return { status: 'success', message: 'Data source is working' };