react-native-mock-tmp-build/src/NativeModules/AppState.js

A fully mocked and test-friendly version of react native

import DeviceEventEmitter from '../plugins/DeviceEventEmitter';

let _appState = 'active';

DeviceEventEmitter.on('appStateDidChange', data => {
  _appState = data._appState;
});

const AppState = {
  getCurrentAppState(callback, error) {
    Promise.resolve({ _appState }).then(callback);
  },

  __setAppState(appState) {
    DeviceEventEmitter.emit('appStateDidChange', { _appState: appState });
  },
};

module.exports = AppState;