Add Coverage Test for MultipleSelectorSection

Summary:
To comply with recent agreement, coverage test for MultipleSelectorSection is added.

Also, add undefined check in `elements.tsx` found while adding the test

Reviewed By: mweststrate

Differential Revision: D21554782

fbshipit-source-id: 7cd868bf16f6105d6f523048f29bdaa052837f45

desktop/plugins/layout/__tests__/MultipleSelectionSection.node.tsx

@@ -0,0 +1,137 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import React from 'react';
+import {render, fireEvent} from '@testing-library/react';
+
+try {
+  jest.mock('../../../app/src/fb/Logger');
+} catch {
+  jest.mock('../../../app/src/fb-stubs/Logger');
+}
+
+import {Element} from 'flipper';
+import MultipleSelectorSection from '../MultipleSelectionSection';
+
+const TITLE_STRING = 'Multiple elements found at the target coordinates';
+const dummyElmentData: Omit<Element, 'id' | 'name'> = {
+  expanded: false,
+  children: [],
+  attributes: [],
+  data: {},
+  decoration: '',
+  extraInfo: {},
+};
+
+test('rendering a single element', () => {
+  const id = 'id1';
+  const name = 'id_name';
+  const element: Element = {...dummyElmentData, id, name};
+  const res = render(
+    <MultipleSelectorSection
+      initialSelectedElement={null}
+      elements={{[id]: element}}
+      onElementSelected={() => {}}
+      onElementHovered={null}
+    />,
+  );
+
+  expect(res.queryByText(TITLE_STRING)).toBeDefined();
+  expect(res.queryAllByText(name).length).toBe(1);
+});
+
+test('collapsing an element', () => {
+  const id = 'id1';
+  const name = 'id_name';
+  const element: Element = {...dummyElmentData, id, name};
+  const res = render(
+    <MultipleSelectorSection
+      initialSelectedElement={null}
+      elements={{[id]: element}}
+      onElementSelected={() => {}}
+      onElementHovered={null}
+    />,
+  );
+
+  expect(res.queryAllByText(name).length).toBe(1);
+
+  // collapse the view
+  fireEvent.click(res.getByText(TITLE_STRING));
+  expect(res.queryAllByText(name).length).toBe(0);
+
+  // re-expand the view
+  fireEvent.click(res.getByText(TITLE_STRING));
+  expect(res.queryAllByText(name).length).toBe(1);
+});
+
+test('clicking on elements', () => {
+  const ids = ['id1', 'id2', 'id3'];
+  const names = ['id_name_first', 'id_name_second', 'id_name_third'];
+  const elements: {[id: string]: Element} = ids.reduce(
+    (acc: {[id: string]: Element}, id, idx) => {
+      acc[id] = {...dummyElmentData, id, name: names[idx]};
+      return acc;
+    },
+    {},
+  );
+  const mockOnElementSelected = jest.fn((_key: string) => {});
+  window.scrollTo = () => {};
+  const res = render(
+    <MultipleSelectorSection
+      initialSelectedElement={null}
+      elements={elements}
+      onElementSelected={mockOnElementSelected}
+      onElementHovered={null}
+    />,
+  );
+
+  const clickingIdx = [0, 1, 2, 1, 0];
+  clickingIdx.forEach((idx) => fireEvent.click(res.getByText(names[idx])));
+
+  // expect all click to call the function
+  expect(mockOnElementSelected.mock.calls.length).toBe(clickingIdx.length);
+  clickingIdx.forEach((valIdx, idx) =>
+    expect(mockOnElementSelected.mock.calls[idx][0]).toBe(ids[valIdx]),
+  );
+});
+
+test('hovering on elements', () => {
+  const ids = ['id1', 'id2', 'id3'];
+  const names = ['id_name_first', 'id_name_second', 'id_name_third'];
+  const elements: {[id: string]: Element} = ids.reduce(
+    (acc: {[id: string]: Element}, id, idx) => {
+      acc[id] = {...dummyElmentData, id, name: names[idx]};
+      return acc;
+    },
+    {},
+  );
+  const mockOnElementSelected = jest.fn((_key: string) => {});
+  const mockOnElementHovered = jest.fn((_key: string | null | undefined) => {});
+  window.scrollTo = () => {};
+  const res = render(
+    <MultipleSelectorSection
+      initialSelectedElement={null}
+      elements={elements}
+      onElementSelected={mockOnElementSelected}
+      onElementHovered={mockOnElementHovered}
+    />,
+  );
+
+  const clickingIdx = [0, 1, 2, 1, 0];
+  clickingIdx.forEach((idx) => fireEvent.mouseOver(res.getByText(names[idx])));
+
+  // expect all hover to call the function
+  expect(mockOnElementHovered.mock.calls.length).toBe(clickingIdx.length);
+  clickingIdx.forEach((valIdx, idx) =>
+    expect(mockOnElementHovered.mock.calls[idx][0]).toBe(ids[valIdx]),
+  );
+
+  // expect no click to be called
+  expect(mockOnElementSelected.mock.calls.length).toBe(0);
+});