Fix warnings in tests (canada-ca#1091)

This commit has a handful of minor tweaks to solve some of the things
generating warnings in the tests.

Author: sleepycat

frontend/src/DomainCard.js

@@ -126,5 +126,5 @@ export function DomainCard({ url, lastRan, ...rest }) {
 
 DomainCard.propTypes = {
   url: string.isRequired,
-  lastRan: string.isRequired,
+  lastRan: string,
 }

frontend/src/__tests__/FloatingMenu.test.js

@@ -8,10 +8,6 @@ import { UserStateProvider } from '../UserState'
 import { MemoryRouter, Route } from 'react-router-dom'
 import { fireEvent } from '@testing-library/dom'
 
-// This defines the window.scrollBy work-around used for firefox on android
-Object.defineProperty(window, 'scrollBy', {
-  value: jest.fn().mockImplementation(() => ({})),
-})
 
 describe('<FloatingMenu>', () => {
   it('renders', async () => {

frontend/src/__tests__/OrganizationCard.test.js

@@ -17,6 +17,7 @@ describe('<OrganizationsCard />', () => {
               <OrganizationCard
                 slug="tbs-sct-gc-ca"
                 name="Treasury Board Secretariat"
+                acronym="TBS"
                 domainCount={7}
               />
             </I18nProvider>

frontend/src/setupTests.js

@@ -1 +1,10 @@
 import '@testing-library/jest-dom'
+
+// This defines the window.scrollBy work-around used for firefox on android
+Object.defineProperty(window, 'scrollBy', {
+  value: jest.fn().mockImplementation(() => ({})),
+})
+
+window.alert = () => {}
+
+window.matchMedia = () => ({})