test: Add test fixtures & implement testDatasource for tag

jest.config.js

@@ -5,4 +5,6 @@ process.env.TZ = 'UTC';
 module.exports = {
   // Jest configuration provided by Grafana scaffolding
   ...require('./.config/jest.config'),
+  // Clear mocks before every test
+  clearMocks: true
 };

package.json

@@ -8,6 +8,7 @@
     "dev": "webpack -w -c ./.config/webpack/webpack.config.ts --env development",
     "test": "jest --watch --onlyChanged",
     "test:ci": "jest --passWithNoTests --maxWorkers 4",
+    "test:template": "npx plop datasource Test && npx tsc --noEmit && rimraf src/datasources/test",
     "lint": "eslint --cache --ignore-path ./.gitignore --ext .js,.jsx,.ts,.tsx .",
     "lint:fix": "npm run lint -- --fix",
     "e2e": "npm exec cypress install && npm exec grafana-e2e run",
@@ -47,6 +48,7 @@
     "identity-obj-proxy": "3.0.0",
     "jest": "^29.5.0",
     "jest-environment-jsdom": "^29.5.0",
+    "jest-mock-extended": "^3.0.4",
     "plop": "^3.1.2",
     "prettier": "^2.8.7",
     "replace-in-file-webpack-plugin": "^1.0.6",

src/datasources/tag/TagDataSource.test.ts

@@ -0,0 +1,26 @@
+import { MockProxy } from 'jest-mock-extended';
+import { TagDataSource } from './TagDataSource';
+import { createDataSource, createFetchError } from 'test/fixtures';
+import { BackendSrv } from '@grafana/runtime';
+
+let ds: TagDataSource, backendSrv: MockProxy<BackendSrv>;
+
+beforeEach(() => {
+  [ds, backendSrv] = createDataSource(TagDataSource);
+});
+
+describe('testDatasource', () => {
+  test('returns success', async () => {
+    backendSrv.get.calledWith('/nitag/v2/tags-count').mockResolvedValue(25);
+
+    const result = await ds.testDatasource();
+
+    expect(result.status).toEqual('success');
+  });
+
+  test('bubbles up exception', async () => {
+    backendSrv.get.calledWith('/nitag/v2/tags-count').mockRejectedValue(createFetchError(400));
+
+    await expect(ds.testDatasource()).rejects.toHaveProperty('status', 400);
+  });
+});

src/datasources/tag/TagDataSource.ts

@@ -4,19 +4,21 @@ import {
   DataSourceApi,
   DataSourceInstanceSettings,
   MutableDataFrame,
-  FieldType,
+  FieldType
 } from '@grafana/data';
 
-import { TestingStatus, getBackendSrv } from '@grafana/runtime';
+import { BackendSrv, TestingStatus, getBackendSrv } from '@grafana/runtime';
 
 import { TagQuery } from './types';
 
 export class TagDataSource extends DataSourceApi<TagQuery> {
   baseUrl: string;
-  constructor(private instanceSettings: DataSourceInstanceSettings) {
+  constructor(
+    private instanceSettings: DataSourceInstanceSettings,
+    private backendSrv: BackendSrv = getBackendSrv()
+  ) {
     super(instanceSettings);
-    // TODO: set base path of the service
-    this.baseUrl = this.instanceSettings.url + '/nifoo/v2';
+    this.baseUrl = this.instanceSettings.url + '/nitag/v2';
   }
 
   async query(options: DataQueryRequest<TagQuery>): Promise<DataQueryResponse> {
@@ -39,8 +41,7 @@ export class TagDataSource extends DataSourceApi<TagQuery> {
   }
 
   async testDatasource(): Promise<TestingStatus> {
-    // TODO: Implement a health and authentication check
-    await getBackendSrv().get(this.baseUrl + '/bar');
+    await this.backendSrv.get(this.baseUrl + '/tags-count');
     return { status: 'success', message: 'Data source connected and authentication successful!' };
   }
 }

src/test/fixtures.ts

@@ -0,0 +1,22 @@
+import { DataSourceInstanceSettings } from '@grafana/data';
+import { BackendSrv, FetchError } from '@grafana/runtime';
+import { mock, MockProxy } from 'jest-mock-extended';
+
+export function createDataSource<T>(
+  ctor: new (instanceSettings: DataSourceInstanceSettings, backendSrv: BackendSrv) => T
+): [T, MockProxy<BackendSrv>] {
+  const mockBackendSrv = mock<BackendSrv>(
+    {},
+    {
+      fallbackMockImplementation: () => {
+        throw new Error('Unexpected request');
+      },
+    }
+  );
+  const ds = new ctor({ url: '' } as DataSourceInstanceSettings, mockBackendSrv);
+  return [ds, mockBackendSrv];
+}
+
+export function createFetchError(status: number): FetchError {
+  return mock<FetchError>({ status });
+}

templates/datasource/{{Name}}DataSource.ts.hbs

@@ -7,13 +7,16 @@ import {
   FieldType,
 } from '@grafana/data';
 
-import { TestingStatus, getBackendSrv } from '@grafana/runtime';
+import { BackendSrv, TestingStatus, getBackendSrv } from '@grafana/runtime';
 
 import { {{Name}}Query } from './types';
 
 export class {{Name}}DataSource extends DataSourceApi<{{Name}}Query> {
   baseUrl: string;
-  constructor(private instanceSettings: DataSourceInstanceSettings) {
+  constructor(
+    private instanceSettings: DataSourceInstanceSettings,
+    private backendSrv: BackendSrv = getBackendSrv()
+  ) {
     super(instanceSettings);
     // TODO: set base path of the service
     this.baseUrl = this.instanceSettings.url + '/nifoo/v2';
@@ -40,7 +43,7 @@ export class {{Name}}DataSource extends DataSourceApi<{{Name}}Query> {
 
   async testDatasource(): Promise<TestingStatus> {
     // TODO: Implement a health and authentication check
-    await getBackendSrv().get(this.baseUrl + '/bar');
+    await this.backendSrv.get(this.baseUrl + '/bar');
     return { status: 'success', message: 'Data source connected and authentication successful!' };
   }
 }