add unit tests for About button on menu bar

src/components/menu-bar/menu-bar.jsx

@@ -141,6 +141,19 @@ MenuItemTooltip.propTypes = {
     isRtl: PropTypes.bool
 };
 
+const AboutButton = props => (
+    <Button
+        className={classNames(styles.menuBarItem, styles.hoverable)}
+        iconClassName={styles.aboutIcon}
+        iconSrc={aboutIcon}
+        onClick={props.onClick}
+    />
+);
+
+AboutButton.propTypes = {
+    onClick: PropTypes.func.isRequired
+};
+
 class MenuBar extends React.Component {
     constructor (props) {
         super(props);
@@ -311,17 +324,8 @@ class MenuBar extends React.Component {
                 {remixMessage}
             </Button>
         );
-        const handleClickAbout = this.props.onClickAbout;
         // Show the About button only if we have a handler for it (like in the desktop app)
-        const aboutButton = handleClickAbout ? (
-            <div className={classNames(styles.menuBarItem, styles.hoverable)}>
-                <img
-                    className={styles.aboutIcon}
-                    onClick={handleClickAbout}
-                    src={aboutIcon}
-                />
-            </div>
-        ) : null;
+        const aboutButton = this.props.onClickAbout ? <AboutButton onClick={this.props.onClickAbout} /> : null;
         return (
             <Box
                 className={classNames(

test/unit/components/menu-bar.test.jsx

+import React from 'react';
+import {mountWithIntl} from '../../helpers/intl-helpers';
+import MenuBar from '../../../src/components/menu-bar/menu-bar';
+import {menuInitialState} from '../../../src/reducers/menus';
+import {LoadingState} from '../../../src/reducers/project-state';
+
+import configureStore from 'redux-mock-store';
+import {Provider} from 'react-redux';
+import VM from 'scratch-vm';
+
+
+describe('MenuBar Component', () => {
+    const store = configureStore()({
+        locales: {
+            isRtl: false,
+            locale: 'en-US'
+        },
+        scratchGui: {
+            menus: menuInitialState,
+            projectState: {
+                loadingState: LoadingState.NOT_LOADED
+            },
+            vm: new VM()
+        }
+    });
+
+    const getComponent = function (props = {}) {
+        return <Provider store={store}><MenuBar {...props} /></Provider>;
+    };
+
+    test('menu bar with no About handler has no About button', () => {
+        const menuBar = mountWithIntl(getComponent());
+        const button = menuBar.find('AboutButton');
+        expect(button.exists()).toBe(false);
+    });
+
+    test('menu bar with an About handler has an About button', () => {
+        const onClickAbout = jest.fn();
+        const menuBar = mountWithIntl(getComponent({onClickAbout}));
+        const button = menuBar.find('AboutButton');
+        expect(button.exists()).toBe(true);
+    });
+
+    test('clicking on About button calls the handler', () => {
+        const onClickAbout = jest.fn();
+        const menuBar = mountWithIntl(getComponent({onClickAbout}));
+        const button = menuBar.find('AboutButton');
+        expect(onClickAbout).toHaveBeenCalledTimes(0);
+        button.simulate('click');
+        expect(onClickAbout).toHaveBeenCalledTimes(1);
+    });
+});