sync-storage/__mocks__/@react-native-community/async-storage/index.js

Synchronous storage for React Native.

let cache = {};

const multi = (arrKeys) => {
  const keys = Object.keys(cache);
  const arr = [];
  for (var i = 0; i < keys.length; i++) {
    if (arrKeys.indexOf(keys[i]) !== -1) {
      arr.push(cache[keys[i]]); 
    }
  }
  return arr;
}

export default {
  multiGet: (keys) => {
    return new Promise((resolve, reject) => {
      return (typeof keys !== 'object')
        ? reject(new Error('keys must be array'))
        : resolve(multi(keys));
    });
  },
  setItem: (key, value) => {
    return new Promise((resolve, reject) => {
      return (typeof key !== 'string' || typeof value !== 'string')
        ? reject(new Error('key and value must be string'))
        : resolve(cache[key] = value);
    });
  },
  getItem: (key, value) => {
    return new Promise((resolve) => {
      return cache.hasOwnProperty(key)
        ? resolve(cache[key])
        : resolve(null);
    });
  },
  removeItem: (key) => {
    return new Promise((resolve, reject) => {
      return cache.hasOwnProperty(key)
        ? resolve(delete cache[key])
        : reject('No such key!');
    });
  },
  clear: (key) => {
    return new Promise((resolve, reject) => resolve(cache = {}));
  },

  getAllKeys: (key) => {
    return new Promise((resolve, reject) => resolve(Object.keys(cache)));
  },
}