[Query Copilot] Add unit tests for Welcome Modal (#1535)

src/setupTests.ts

@@ -1,7 +1,8 @@
+import { initializeIcons } from "@fluentui/react";
 import { configure } from "enzyme";
 import Adapter from "enzyme-adapter-react-16";
 import "jest-canvas-mock";
-import { initializeIcons } from "@fluentui/react";
+import enableHooks from "jest-react-hooks-shallow";
 import { TextDecoder, TextEncoder } from "util";
 configure({ adapter: new Adapter() });
 initializeIcons();
@@ -10,6 +11,30 @@ if (typeof window.URL.createObjectURL === "undefined") {
   Object.defineProperty(window.URL, "createObjectURL", { value: () => {} });
 }
 
+enableHooks(jest, { dontMockByDefault: true });
+
+const localStorageMock = (function () {
+  let store: { [key: string]: string } = {};
+  return {
+    getItem: function (key: string) {
+      return store[key] || null;
+    },
+    setItem: function (key: string, value: string) {
+      store[key] = value.toString();
+    },
+    removeItem: function (key: string) {
+      delete store[key];
+    },
+    clear: function () {
+      store = {};
+    },
+  };
+})();
+
+Object.defineProperty(window, "localStorage", {
+  value: localStorageMock,
+});
+
 // TODO Remove when jquery and documentdbclient SDK are removed
 (<any>window).$ = (<any>window).jQuery = require("jquery");
 (<any>global).$ = (<any>global).$.jQuery = require("jquery");