Genarrative/src/persistence/storage.test.ts

import { describe, expect, it } from 'vitest';

import {
  isRecord,
  type JsonStorage,
  readStoredJson,
  removeStoredJson,
  writeStoredJson,
} from './storage';

function createMemoryStorage(): JsonStorage {
  const values = new Map<string, string>();

  return {
    getItem(key) {
      return values.has(key) ? values.get(key)! : null;
    },
    setItem(key, value) {
      values.set(key, value);
    },
    removeItem(key) {
      values.delete(key);
    },
  };
}

describe('storage helpers', () => {
  it('reads parsed json values from storage', () => {
    const storage = createMemoryStorage();

    writeStoredJson({
      key: 'example',
      value: { value: 42 },
      storage,
    });

    const result = readStoredJson({
      key: 'example',
      storage,
      parse: (value) =>
        isRecord(value) && typeof value.value === 'number' ? value.value : null,
    });

    expect(result).toBe(42);
  });

  it('returns null when persisted json cannot be parsed', () => {
    const storage = createMemoryStorage();
    storage.setItem('broken', '{not-valid-json');

    const result = readStoredJson({
      key: 'broken',
      storage,
      parse: () => 'unreachable',
    });

    expect(result).toBeNull();
  });

  it('removes persisted values', () => {
    const storage = createMemoryStorage();

    writeStoredJson({
      key: 'example',
      value: { value: 'keep' },
      storage,
    });
    removeStoredJson('example', storage);

    expect(storage.getItem('example')).toBeNull();
  });
});