graph-crdt/dist/Node/merge.test.js

A Delta State Graph CRDT variant

'use strict';

var _slicedToArray2 = require('babel-runtime/helpers/slicedToArray');

var _slicedToArray3 = _interopRequireDefault(_slicedToArray2);

var _toConsumableArray2 = require('babel-runtime/helpers/toConsumableArray');

var _toConsumableArray3 = _interopRequireDefault(_toConsumableArray2);

var _expect = require('expect');

var _expect2 = _interopRequireDefault(_expect);

var _index = require('./index');

var _index2 = _interopRequireDefault(_index);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/* eslint-env mocha */
describe('A node merge', function () {
  var node = void 0;

  beforeEach(function () {
    node = new _index2.default();
  });

  it('namespaces to avoid conflicts', function () {
    node.merge({ read: 'not a function' });
    (0, _expect2.default)(node.value).toBeA(Function);
  });

  it('converts POJOs into Nodes', function () {
    node.merge({ data: 'success' });
    (0, _expect2.default)(node.value('data')).toBe('success');
  });

  it('uses the same node ID for new change nodes', function () {
    var _node$merge = node.merge({}),
        update = _node$merge.update,
        history = _node$merge.history;

    var _node$meta = node.meta(),
        uid = _node$meta.uid;

    (0, _expect2.default)(update.meta()).toContain({ uid: uid });
    (0, _expect2.default)(history.meta()).toContain({ uid: uid });
  });

  describe('within operating state bounds', function () {
    it('adds all new properties', function () {
      var update = _index2.default.from({ data: true });
      node.merge(update);

      var keys = [].concat((0, _toConsumableArray3.default)(node)).map(function (_ref) {
        var _ref2 = (0, _slicedToArray3.default)(_ref, 1),
            key = _ref2[0];

        return key;
      });
      (0, _expect2.default)(keys).toContain('data');
    });

    it('updates existing properties', function () {
      var incoming = _index2.default.from({ data: false });
      node.merge(incoming);
      (0, _expect2.default)(node.value('data')).toBe(false);

      incoming.merge({ data: true });
      node.merge(incoming);

      (0, _expect2.default)(node.value('data')).toBe(true);
    });

    it('emits `update` after updates', function () {
      var spy = (0, _expect.createSpy)();
      node.on('update', spy);

      node.merge({ data: 'yep' });

      var _spy$calls$0$argument = (0, _slicedToArray3.default)(spy.calls[0].arguments, 1),
          value = _spy$calls$0$argument[0];

      (0, _expect2.default)(value).toBeA(_index2.default);

      var object = value.snapshot();
      (0, _expect2.default)(object).toEqual({ data: 'yep' });
    });

    it('returns the updates', function () {
      var _node$merge2 = node.merge({ data: 'yep' }),
          update = _node$merge2.update;

      (0, _expect2.default)(update).toBeA(_index2.default);

      var object = update.snapshot();
      (0, _expect2.default)(object).toEqual({
        data: 'yep'
      });
    });

    it('does not emit `update` without updates', function () {
      var spy = (0, _expect.createSpy)();
      node.on('update', spy);

      // No properties.
      node.merge({});

      (0, _expect2.default)(spy).toNotHaveBeenCalled();
    });

    it('does not emit `update` for the same update', function () {
      var spy = (0, _expect.createSpy)();
      node.on('update', spy);

      var update = _index2.default.from({ update: true });

      node.merge(update);
      node.merge(update);

      (0, _expect2.default)(spy.calls.length).toBe(1);
    });

    it('merges other nodes', function () {
      var weather = new _index2.default({ uid: 'weather' });
      weather.merge({ condition: 'sunny', temp: 65 });

      var change = new _index2.default({ uid: 'weather' });
      change.merge(weather);
      change.merge({ temp: 70 });

      weather.merge(change);

      (0, _expect2.default)(weather.state('temp')).toBe(2);
      (0, _expect2.default)(weather.value('temp')).toBe(70);
    });
  });

  describe('in historical state', function () {
    var incoming = void 0;

    beforeEach(function () {
      incoming = _index2.default.create();
    });

    it('does not overwrite more recent properties', function () {
      // Stale update.
      incoming.merge({ hello: 'Mars' });
      incoming.meta('hello').state = 1;

      var update = _index2.default.from({ hello: 'World' });
      update.meta('hello').state = 2;

      node.merge(update);
      node.merge(incoming);

      (0, _expect2.default)(node.value('hello')).toBe('World');
    });

    it('adds new properties', function () {
      // Really old state, but it's new to `node`.
      incoming.merge({ success: true });
      incoming.meta('success').state = 10;

      node.merge(incoming);

      (0, _expect2.default)(node.value('success')).toBe(true);
    });

    it('returns the history', function () {
      incoming.merge({ old: true });
      incoming.meta('old').state = 1;
      node.merge({ old: false });
      node.meta('old').state = 2;

      var _node$merge3 = node.merge(incoming),
          history = _node$merge3.history;

      (0, _expect2.default)(history).toBeA(_index2.default);
      var object = history.snapshot();

      (0, _expect2.default)(object).toEqual({ old: true });
    });

    it('includes overwritten values in history', function () {
      node.merge({ old: true });

      var _node$merge4 = node.merge({ old: false }),
          history = _node$merge4.history;

      var object = history.snapshot();
      (0, _expect2.default)(object).toEqual({ old: true });
    });

    it('emits `history` if updates are outdated', function () {
      incoming.merge({ data: 'old state' });
      incoming.meta('data').state = 1;

      node.merge({ data: 'new state' });
      node.meta('data').state = 2;

      var spy = (0, _expect.createSpy)();
      node.on('history', spy);

      node.merge(incoming);

      var _spy$calls$0$argument2 = (0, _slicedToArray3.default)(spy.calls[0].arguments, 1),
          history = _spy$calls$0$argument2[0];

      (0, _expect2.default)(history).toBeA(_index2.default);

      var object = history.snapshot();
      (0, _expect2.default)(object).toEqual({ data: 'old state' });
    });

    it('does not emit `history` without stale updates', function () {
      var spy = (0, _expect.createSpy)();
      node.on('history', spy);

      incoming.merge({ 'new property': 'yeah' });
      incoming.meta('new property').state = 1;

      node.merge({ hello: 'Earth' });

      node.merge(incoming);

      (0, _expect2.default)(spy).toNotHaveBeenCalled();
    });
  });

  describe('conflict', function () {
    var conflict = void 0;

    beforeEach(function () {
      conflict = new _index2.default();

      node.merge({ value: '9' });
      conflict.merge({ value: '5' });

      // Same state.
      node.meta('value').state = conflict.meta('value').state;
    });

    it('is ignored if it loses', function () {
      var _node$merge5 = node.merge(conflict),
          update = _node$merge5.update,
          history = _node$merge5.history;

      (0, _expect2.default)(update.snapshot()).toEqual({});
      (0, _expect2.default)(history.snapshot()).toEqual({});
    });

    it('triggers an update if it wins', function () {
      node.meta('value').value = '1';

      var _node$merge6 = node.merge(conflict),
          update = _node$merge6.update;

      (0, _expect2.default)(update.snapshot()).toEqual({ value: '5' });
    });

    it('emits `conflict` if it wins', function () {
      var spy = (0, _expect.createSpy)();
      node.on('conflict', spy);

      var current = node.meta('value');
      var update = conflict.meta('value');

      current.value = '1';

      node.merge(conflict);

      (0, _expect2.default)(spy).toHaveBeenCalled();
      (0, _expect2.default)(spy).toHaveBeenCalledWith(update, current);
    });

    it('does not emit `conflict` if it loses', function () {
      var spy = (0, _expect.createSpy)();
      node.on('conflict', spy);

      node.merge(conflict);

      (0, _expect2.default)(spy).toNotHaveBeenCalled();
    });
  });
});