add mock state for unit tests

src/components/App/App.test.tsx

@@ -13,7 +13,6 @@ describe("App", () => {
   it("renders Loader when userProfile not loaded", () => {
     const { container } = setup({
       userProfile: {},
-      users: { list: null },
     });
     const app = container.querySelector(".loader");
     expect(app).toBeInTheDocument();
@@ -23,7 +22,6 @@ describe("App", () => {
       userProfile: {
         username: "Steve",
       },
-      users: { list: null },
     });
     const app = container.querySelector(".app");
     expect(app).toBeInTheDocument();

src/pages/LandingPage/LandingPage.test.tsx

@@ -12,10 +12,7 @@ const setup = (initialState = {}) =>
 
 describe("LandingPage", () => {
   it("renders", () => {
-    setup({
-      userProfile: {},
-      users: { list: null },
-    });
+    setup();
 
     const heading = screen.getByText("Landing page");
     expect(heading).toBeInTheDocument();

src/state/rootReducer.ts

@@ -3,7 +3,9 @@ import { combineReducers } from "@reduxjs/toolkit";
 import userProfile from "./userProfile/reducer";
 import users from "./users/reducer";
 
-const rootReducer = combineReducers({ userProfile, users });
+export const reducers = { userProfile, users } as const;
+
+const rootReducer = combineReducers(reducers);
 
 export type RootState = ReturnType<typeof rootReducer>;
 export default rootReducer;

src/state/userProfile/selectors.test.ts

@@ -1,15 +1,15 @@
 import { getUsername } from "./selectors";
-
+import mockState from "utilities/test/mockState";
 import { RootState } from "../rootReducer";
 
 describe("UserProfile selectors", () => {
   describe("getUsername", () => {
     it("should return username", () => {
       const state: RootState = {
+        ...mockState,
         userProfile: {
           username: "Steve",
         },
-        users: { list: null },
       };
       expect(getUsername(state)).toBe("Steve");
     });

src/utilities/test/mockState.ts

@@ -0,0 +1,9 @@
+import { initialState as userProfileInitialState } from "state/userProfile/reducer";
+import { initialState as usersInitialState } from "state/users/reducer";
+
+const state = {
+  userProfile: userProfileInitialState,
+  users: usersInitialState,
+};
+
+export default state;

src/utilities/test/renderConnected.tsx

@@ -4,6 +4,8 @@ import { Provider } from "react-redux";
 import configureStore, { MockStore } from "redux-mock-store";
 import thunk from "redux-thunk";
 
+import { reducers } from "state/rootReducer";
+
 interface RenderConnected {
   ui: JSX.Element;
   initialState: Record<string, unknown>;
@@ -18,7 +20,7 @@ const middleware = [thunk];
 const mockStore = configureStore(middleware);
 
 export const makeStore = (initialState: Record<string, unknown>): MockStore =>
-  mockStore(initialState);
+  mockStore({ ...reducers, ...initialState });
 
 const renderConnected = ({
   ui,