feat(dashboard): Add thumbnails to dashboard edit draggable chart list (

apache#20528)

* Add chart thumbnails to dashboard edit draggable charts.

* Reorganize hierarchy and add tests.

* Incorporate review suggestions.

* Update design and add tooltips.

* Fix missing thumbnails.

* Fix tests.

* Fix moving viz type label.

* Convert AddSliceCard to TS, update hierarchy.

superset-frontend/src/dashboard/actions/sliceEntities.js

@@ -72,6 +72,7 @@ export function fetchSlices(
         'id',
         'params',
         'slice_name',
+        'thumbnail_url',
         'url',
         'viz_type',
       ],
@@ -114,6 +115,7 @@ export function fetchSlices(
           viz_type: slice.viz_type,
           modified: slice.changed_on_delta_humanized,
           changed_on_humanized: slice.changed_on_delta_humanized,
+          thumbnail_url: slice.thumbnail_url,
         };
       });
 

superset-frontend/src/dashboard/components/AddSliceCard/AddSliceCard.test.tsx

@@ -0,0 +1,62 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import React from 'react';
+import { FeatureFlag } from '@superset-ui/core';
+import { act, render, screen } from 'spec/helpers/testing-library';
+import AddSliceCard from '.';
+
+jest.mock('src/components/DynamicPlugins', () => ({
+  usePluginContext: () => ({
+    mountedPluginMetadata: { table: { name: 'Table' } },
+  }),
+}));
+
+const mockedProps = {
+  visType: 'table',
+  sliceName: '-',
+};
+
+declare const global: {
+  featureFlags: Record<string, boolean>;
+};
+
+test('do not render thumbnail if feature flag is not set', async () => {
+  global.featureFlags = {
+    [FeatureFlag.THUMBNAILS]: false,
+  };
+
+  await act(async () => {
+    render(<AddSliceCard {...mockedProps} />);
+  });
+
+  expect(screen.queryByTestId('thumbnail')).not.toBeInTheDocument();
+});
+
+test('render thumbnail if feature flag is set', async () => {
+  global.featureFlags = {
+    [FeatureFlag.THUMBNAILS]: true,
+  };
+
+  await act(async () => {
+    render(<AddSliceCard {...mockedProps} />);
+  });
+
+  expect(screen.queryByTestId('thumbnail')).toBeInTheDocument();
+});