testReducer.js

import update from 'immutability-helper';

const testReducer = (state = {}, action) => {

    switch (action.type) {

        case 'COMPUTE_AMOUNT':
            action.paylod.amount = action.paylod.rate * action.paylod.quantity

        return { ...state, ...action.paylod }

        default:
            return state;
    }
}

export default testReducer;