redux store

rootReducer.js

import { combineReducers } from "redux";
import testReducer from "./testReducer";
import { reducer as formReducer } from "redux-form";
import { reducer as toastrReducer } from "react-redux-toastr";

const rootReducer = combineReducers({
  test: testReducer,
  form: formReducer,
  toastr: toastrReducer
});

export default rootReducer;

store.js

import { createStore, applyMiddleware } from "redux";
import { composeWithDevTools } from "redux-devtools-extension";
import rootReducer from "../../app/reducers/rootReducer";
import thunk from "redux-thunk";

export const configureStore = preloadedState => {
  const middleWare = [thunk];
  const middleWareEnahcer = applyMiddleware(...middleWare);

  const storeEnhancer = [middleWareEnahcer];

  const composeEnahncer = composeWithDevTools(...storeEnhancer);

  const store = createStore(rootReducer, preloadedState, composeEnahncer);

  return store;
};

//in Index.js 
import { configureStore } from "./location";
const store = configureStore(); // pass this to Provider