added jest test

Author: jloleysens

x-pack/plugins/reporting/server/lib/screenshots/get_render_error.test.ts

@@ -0,0 +1,82 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { HeadlessChromiumDriver } from '../../browsers';
+import {
+  createMockBrowserDriverFactory,
+  createMockConfig,
+  createMockConfigSchema,
+  createMockLayoutInstance,
+  createMockLevelLogger,
+  createMockReportingCore,
+} from '../../test_helpers';
+import { CaptureConfig } from '../../types';
+import { LayoutInstance } from '../layouts';
+import { LevelLogger } from '../level_logger';
+import { getRenderErrors } from './get_render_errors';
+
+describe('getRenderErrors', () => {
+  let captureConfig: CaptureConfig;
+  let layout: LayoutInstance;
+  let logger: jest.Mocked<LevelLogger>;
+  let browser: HeadlessChromiumDriver;
+
+  beforeEach(async () => {
+    const schema = createMockConfigSchema();
+    const config = createMockConfig(schema);
+    const core = await createMockReportingCore(schema);
+
+    captureConfig = config.get('capture');
+    layout = createMockLayoutInstance(captureConfig);
+    logger = createMockLevelLogger();
+
+    await createMockBrowserDriverFactory(core, logger, {
+      evaluate: jest.fn(
+        async <T extends (...args: unknown[]) => unknown>({
+          fn,
+          args,
+        }: {
+          fn: T;
+          args: Parameters<T>;
+        }) => fn(...args)
+      ),
+      getCreatePage: (driver) => {
+        browser = driver;
+
+        return jest.fn();
+      },
+    });
+  });
+
+  afterEach(() => {
+    document.body.innerHTML = '';
+  });
+
+  it('should extract the error messages', async () => {
+    document.body.innerHTML = `
+      <renderedSelector data-render-error="a test error" />
+      <renderedSelector data-render-error="a test error" />
+      <renderedSelector data-render-error="a test error" />
+      <renderedSelector data-render-error="a test error" />
+    `;
+
+    await expect(getRenderErrors(browser, layout, logger)).resolves.toEqual([
+      'a test error',
+      'a test error',
+      'a test error',
+      'a test error',
+    ]);
+  });
+
+  it('should extract the error messages, even when there are none', async () => {
+    document.body.innerHTML = `
+      <renderedSelector />
+    `;
+
+    await expect(getRenderErrors(browser, layout, logger)).resolves.toEqual([]);
+  });
+});