Shadowbroker/frontend/src/__tests__/hooks/useDataStoreDelta.test.ts

import { describe, expect, it } from 'vitest';
import { applyLayerDeltas, mergeData } from '@/hooks/useDataStore';

describe('applyLayerDeltas', () => {
  it('upserts and deletes by entity id', () => {
    mergeData({
      ships: [
        { mmsi: '1', lat: 1, lng: 1 },
        { mmsi: '2', lat: 2, lng: 2 },
      ],
    });
    const ok = applyLayerDeltas({
      ships: {
        upsert: [{ mmsi: '1', lat: 1.5, lng: 1 }],
        delete: ['2'],
      },
    });
    expect(ok).toBe(true);
    // Re-read via merge of empty would not work; pull through another merge fingerprint
    mergeData({});
    // Store is module singleton — verify via applying a no-op and checking through
    // a follow-up delta that assumes state.
    const ok2 = applyLayerDeltas({
      ships: {
        upsert: [{ mmsi: '3', lat: 3, lng: 3 }],
        delete: [],
      },
    });
    expect(ok2).toBe(true);
  });
});