Mock withTranslations as per https://react.i18next.com/misc/testing

__tests__/src/components/App.test.js

@@ -9,6 +9,8 @@ import { App } from '../../../src/components/App';
 import settings from '../../../src/config/settings';
 import i18n from '../../../src/i18n';
 
+jest.unmock('react-i18next');
+
 /** */
 function createWrapper(props) {
   return shallow(

__tests__/src/lib/MiradorViewer.test.js

 import ReactDOM from 'react-dom';
 import MiradorViewer from '../../../src/lib/MiradorViewer';
 
+jest.unmock('react-i18next');
+
 describe('MiradorViewer', () => {
   let instance;
   beforeAll(() => {

setupJest.js

@@ -32,3 +32,13 @@ global.IntersectionObserver = IntersectionObserverPolyfill;
 global.Image = window.Image;
 
 Enzyme.configure({ adapter: new Adapter() });
+
+jest.mock('react-i18next', () => ({
+  // this mock makes sure any components using the translate HoC receive the t function as a prop
+  withTranslation: () => (Component) => {
+    Component.defaultProps = { // eslint-disable-line no-param-reassign
+      ...Component.defaultProps, t: k => k,
+    };
+    return Component;
+  },
+}));