test(ui): fix react-i18next warning in jest (#105)

packages/ui/src/__mocks__/react-i18next.js

@@ -0,0 +1,59 @@
+// Copied from https://github.com/i18next/react-i18next/blob/c533ffe092470b58769586681abfc2cf4ecf0b56/example/test-jest/src/__mocks__/react-i18next.js
+/* eslint-disable unicorn/prefer-module */
+const React = require('react');
+const reactI18next = require('react-i18next');
+
+const hasChildren = (node) => node && (node.children || (node.props && node.props.children));
+
+const getChildren = (node) =>
+  node && node.children ? node.children : node.props && node.props.children;
+
+const renderNodes = (reactNodes) => {
+  if (typeof reactNodes === 'string') {
+    return reactNodes;
+  }
+
+  return Object.keys(reactNodes).map((key, i) => {
+    const child = reactNodes[key];
+    const isElement = React.isValidElement(child);
+
+    if (typeof child === 'string') {
+      return child;
+    }
+
+    if (hasChildren(child)) {
+      const inner = renderNodes(getChildren(child));
+      // eslint-disable-next-line react/no-array-index-key
+      return React.cloneElement(child, { ...child.props, key: i }, inner);
+    }
+
+    if (typeof child === 'object' && !isElement) {
+      return Object.keys(child).reduce((string, childKey) => `${string}${child[childKey]}`, '');
+    }
+
+    return child;
+  });
+};
+
+const useMock = [(k) => k, {}];
+useMock.t = (k) => k;
+useMock.i18n = {};
+
+const withTranslation = (Component) => (props) => <Component t={(k) => k} {...props} />;
+
+module.exports = {
+  // This mock makes sure any components using the translate HoC receive the t function as a prop
+  withTranslation: () => withTranslation,
+  Trans: ({ children }) =>
+    Array.isArray(children) ? renderNodes(children) : renderNodes([children]),
+  Translation: ({ children }) => children((k) => k, { i18n: {} }),
+  useTranslation: () => useMock,
+
+  // Mock if needed
+  I18nextProvider: reactI18next.I18nextProvider,
+  initReactI18next: reactI18next.initReactI18next,
+  setDefaults: reactI18next.setDefaults,
+  getDefaults: reactI18next.getDefaults,
+  setI18n: reactI18next.setI18n,
+  getI18n: reactI18next.getI18n,
+};