Prometheus: Default support labels value endpoint with match param when prom type and version not set (#84778)

* default to support labels match endpoint

* add test and fix tests

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

@@ -24,7 +24,7 @@ import {
   prometheusSpecialRegexEscape,
 } from './datasource';
 import PromQlLanguageProvider from './language_provider';
-import { PrometheusCacheLevel, PromOptions, PromQuery, PromQueryRequest } from './types';
+import { PromApplication, PrometheusCacheLevel, PromOptions, PromQuery, PromQueryRequest } from './types';
 
 const fetchMock = jest.fn().mockReturnValue(of(createDefaultPromResponse()));
 
@@ -98,6 +98,13 @@ describe('PrometheusDatasource', () => {
     });
   });
 
+  describe('Type and version', () => {
+    it('Default support labels match endpoint over series when type and version not set', () => {
+      const labelsMatchSupport = ds.hasLabelsMatchAPISupport();
+      expect(labelsMatchSupport).toBe(true);
+    });
+  });
+
   describe('Query', () => {
     it('throws if using direct access', async () => {
       const instanceSettings = {
@@ -108,6 +115,8 @@ describe('PrometheusDatasource', () => {
         access: 'direct',
         jsonData: {
           customQueryParameters: '',
+          prometheusVersion: '2.20.0',
+          prometheusType: PromApplication.Prometheus,
         },
       } as unknown as DataSourceInstanceSettings<PromOptions>;
       const range = { from: time({ seconds: 63 }), to: time({ seconds: 183 }) };

public/app/plugins/datasource/prometheus/datasource.ts

@@ -189,9 +189,9 @@ export class PrometheusDatasource
   }
 
   _isDatasourceVersionGreaterOrEqualTo(targetVersion: string, targetFlavor: PromApplication): boolean {
-    // User hasn't configured flavor/version yet, default behavior is to not support features that require version configuration when not provided
+    // User hasn't configured flavor/version yet, default behavior is to support labels match api support
     if (!this.datasourceConfigurationPrometheusVersion || !this.datasourceConfigurationPrometheusFlavor) {
-      return false;
+      return true;
     }
 
     if (targetFlavor !== this.datasourceConfigurationPrometheusFlavor) {

public/app/plugins/datasource/prometheus/metric_find_query.test.ts

@@ -23,7 +23,11 @@ const instanceSettings = {
   uid: 'ABCDEF',
   user: 'test',
   password: 'mupp',
-  jsonData: { httpMethod: 'GET' },
+  jsonData: {
+    httpMethod: 'GET',
+    prometheusVersion: '2.20.0',
+    prometheusType: PromApplication.Prometheus,
+  },
 } as Partial<DataSourceInstanceSettings<PromOptions>> as DataSourceInstanceSettings<PromOptions>;
 
 const raw: TimeRange = {