Postgres: Fix test datasource always returns success (#43762)

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

@@ -0,0 +1,66 @@
+import { backendSrv } from 'app/core/services/backend_srv';
+import { of, throwError } from 'rxjs';
+import { createFetchResponse } from 'test/helpers/createFetchResponse';
+import { PostgresDatasource } from './datasource';
+
+jest.mock('@grafana/runtime', () => ({
+  ...(jest.requireActual('@grafana/runtime') as any),
+  getBackendSrv: () => backendSrv,
+  getTemplateSrv: () => ({
+    replace: (val: string): string => {
+      return val;
+    },
+  }),
+}));
+
+describe('Postgres datasource', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  describe('when performing testDatasource call', () => {
+    it('should return the error from the server', async () => {
+      setupFetchMock(
+        undefined,
+        throwError(() => ({
+          status: 400,
+          statusText: 'Bad Request',
+          data: {
+            results: {
+              meta: {
+                error: 'db query error: pq: password authentication failed for user "postgres"',
+                frames: [
+                  {
+                    schema: {
+                      refId: 'meta',
+                      meta: {
+                        executedQueryString: 'SELECT 1',
+                      },
+                      fields: [],
+                    },
+                    data: {
+                      values: [],
+                    },
+                  },
+                ],
+              },
+            },
+          },
+        }))
+      );
+
+      const ds = new PostgresDatasource({ name: '', id: 0, jsonData: {} } as any);
+      const result = await ds.testDatasource();
+      expect(result.status).toEqual('error');
+      expect(result.message).toEqual('db query error: pq: password authentication failed for user "postgres"');
+    });
+  });
+});
+
+function setupFetchMock(response: any, mock?: any) {
+  const defaultMock = () => mock ?? of(createFetchResponse(response));
+
+  const fetchMock = jest.spyOn(backendSrv, 'fetch');
+  fetchMock.mockImplementation(defaultMock);
+  return fetchMock;
+}

public/app/plugins/datasource/postgres/datasource.ts

@@ -167,16 +167,37 @@ export class PostgresDatasource extends DataSourceWithBackend<PostgresQuery, Pos
     );
   }
 
+  private _metaRequest(rawSql: string) {
+    const refId = 'meta';
+    const range = this.timeSrv.timeRange();
+    const query = {
+      refId: refId,
+      datasource: this.getRef(),
+      rawSql,
+      format: 'table',
+    };
+    return getBackendSrv().fetch<BackendDataSourceResponse>({
+      url: '/api/ds/query',
+      method: 'POST',
+      data: {
+        from: range.from.valueOf().toString(),
+        to: range.to.valueOf().toString(),
+        queries: [query],
+      },
+      requestId: refId,
+    });
+  }
+
   getVersion(): Promise<any> {
-    return this.metricFindQuery("SELECT current_setting('server_version_num')::int/100", {});
+    return lastValueFrom(this._metaRequest("SELECT current_setting('server_version_num')::int/100"));
   }
 
   getTimescaleDBVersion(): Promise<any> {
-    return this.metricFindQuery("SELECT extversion FROM pg_extension WHERE extname = 'timescaledb'", {});
+    return lastValueFrom(this._metaRequest("SELECT extversion FROM pg_extension WHERE extname = 'timescaledb'"));
   }
 
   testDatasource(): Promise<any> {
-    return this.metricFindQuery('SELECT 1', {})
+    return lastValueFrom(this._metaRequest('SELECT 1'))
       .then(() => {
         return { status: 'success', message: 'Database Connection OK' };
       })