When floating loading spinner isn't visible, don't render it

ts/components/conversation/TimelineFloatingHeader.stories.tsx

@@ -0,0 +1,41 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import * as React from 'react';
+import { storiesOf } from '@storybook/react';
+import { isBoolean } from 'lodash';
+import { boolean } from '@storybook/addon-knobs';
+
+import { setupI18n } from '../../util/setupI18n';
+import enMessages from '../../../_locales/en/messages.json';
+
+import type { PropsType } from './TimelineFloatingHeader';
+import { TimelineFloatingHeader } from './TimelineFloatingHeader';
+
+const i18n = setupI18n('en', enMessages);
+
+function booleanOr(value: boolean | undefined, defaultValue: boolean): boolean {
+  return isBoolean(value) ? value : defaultValue;
+}
+
+const createProps = (overrideProps: Partial<PropsType> = {}): PropsType => ({
+  isLoading: boolean('isLoading', booleanOr(overrideProps.isLoading, false)),
+  style: overrideProps.style,
+  visible: boolean('visible', booleanOr(overrideProps.visible, false)),
+  i18n,
+  timestamp: overrideProps.timestamp || Date.now(),
+});
+
+const stories = storiesOf('Components/TimelineFloatingHeader', module);
+
+stories.add('Visible', () => {
+  return <TimelineFloatingHeader {...createProps({ visible: true })} />;
+});
+
+stories.add('Loading', () => {
+  return (
+    <TimelineFloatingHeader
+      {...createProps({ visible: true, isLoading: true })}
+    />
+  );
+});