恢复前校验备份清单

任务

依次核对校验和、字节数与对象数量，一次性列出全部不一致项，让恢复流程在开始之前就停下。

契约

• 输入：JSON 对象：{ backup: { checksum, sizeBytes, objectCount }, manifest: { checksum, sizeBytes, minimumObjects } }
• 输出：JSON 对象：{ verified: boolean, mismatches: string[] }

样例

1. 输入 {"backup":{"checksum":"sha256:abc","sizeBytes":1024,"objectCount":40},"manifest":{"checksum":"sha256:abc","sizeBytes":1024,"minimumObjects":10}} -> 期望 {"verified":true,"mismatches":[]}。校验和、体积与对象数都满足清单要求。
2. 输入 {"backup":{"checksum":"sha256:def","sizeBytes":900,"objectCount":4},"manifest":{"checksum":"sha256:abc","sizeBytes":1024,"minimumObjects":10}} -> 期望 {"verified":false,"mismatches":["checksum","object-count","size"]}。三项检查全部失败，并被一起按序报告。

参考实现

function solve({ backup, manifest }) {
      const mismatches = [];
      if (backup.checksum !== manifest.checksum) mismatches.push('checksum');
      if (backup.sizeBytes !== manifest.sizeBytes) mismatches.push('size');
      if (backup.objectCount < manifest.minimumObjects) mismatches.push('object-count');
      return { verified: mismatches.length === 0, mismatches: mismatches.sort() };
    }

为什么有效

恢复演练失败的根源，往往是没人验证过的产物。先校验清单，能把“赌一把能恢复”变成明确的前置条件。

要一次性报告所有失败项，而不是遇到第一个就停下；恢复团队需要完整的信息。