Let's look at how to set up our app so that we can use our debugging tools. To start with, we'll require a simple change in the store creation code, adding a couple of lines, as shown here:

// Source file: src/regionsStyledApp/store.js

/* @flow */

import { createStore, applyMiddleware } from "redux";
import thunk from "redux-thunk";
import { composeWithDevTools } from "redux-devtools-extension";

import { reducer } from "./world.reducer";

export const store = createStore(
    reducer,
    composeWithDevTools(applyMiddleware(thunk))
);

Just for the sake of it—so that we can actually get some debugging messages – I added sundry console.log() and console.error() calls throughout the code. For consistency, I wanted to use debug (from https://www.npmjs.com/package/debug), as we did earlier in the book, but it won't work, because it requires LocalStorage, and in RN you get AsyncStorage instead, with a different API. Just as an example, we'll look at some log output from world.actions.js. I didn't bother logging the output from successful API calls, because we'll be getting that through react-native-debugger, as we'll see:

// Source file: src/regionsStyledApp/world.actions.js

.
.
.

export const getCountries = () => async dispatch => {
    console.log("getCountries: called");
    try {
        dispatch(countriesRequest());
        const result = await getCountriesAPI();
        dispatch(countriesSuccess(result.data));
    } catch (e) {
        console.error("getCountries: failure!");
        dispatch(countriesFailure());
    }
};

export const getRegions = (country: string) => async dispatch => {
    console.log("getRegions: called with ", country);
    if (country) {
        try {
            dispatch(regionsRequest(country));
            const result = await getRegionsAPI(country);
            dispatch(regionsSuccess(result.data));
        } catch (e) {
            console.error("getRegions: failure with API!");
            dispatch(regionsFailure());
        }
    } else {
        console.error("getRegions: failure, no country!");
        dispatch(regionsFailure());
    }
};

We have everything in place; let's try it out.