Split a 200-Line Function into Testable Steps

Added 2026-10-28

Split a 200-Line Function into Testable Steps — Chinese original prompt

你是一名做过多次大重构的资深工程师。我有个两百多行的长函数，没人敢动，请帮我把它拆成可测试的小步骤。

[函数代码]：完整粘贴，包含它依赖的全局变量
[调用方]：谁在什么场景调用它
[现有测试]：有几个、覆盖了什么
[不能改变的行为]：对外返回值、日志格式、调用时序

输出结构：
1. 行为快照：输入到输出，以及所有副作用（写库、日志、发请求、读时间、随机数）
2. 拆分方案：每一步的职责、入参、返回、可单独测试的点，最多 5 步
3. 迁移顺序：每步都能独立提交并回滚，标明哪步风险最高
4. 需要新增的最小测试用例：每条写清输入与断言

验收标准：拆分后对外行为完全不变；每步可脱离上下文单独调用；不引入新框架或新依赖；涉及副作用的步骤必须显式传参而不是读全局。无法确认的行为单独列出，不要替我决定。

Site original

Chinese original

Replace these placeholders 4

Swap the bracketed parts for your own details before sending.

[函数代码]
[调用方]
[现有测试]
[不能改变的行为]

How to use

没有现成测试时别直接重构，先让它生成行为快照用例，否则拆完很难证明行为没变。

Try tweaking it

Have it restate requirements and constraints before writing code.
Ask for the smallest change plus a rollback path, not a full-file rewrite.

What you should get

A minimal, runnable change with copy-ready code
Impact list: which files and call sites must follow

Common mistakes

Asking it to touch ten files at once, then losing track of what broke what.
Pasting only the error, with no code or version, and getting an unfixable answer.

How to check the output

The change runs, can be rolled back, and touches nothing unrelated.
Edge cases (empty, oversized, concurrent) are covered or explained.

Where it works

Good for: having it restate requirements and constraints, then propose the smallest runnable change.
Watch out: include versions and a minimal reproduction with the error, or the fix may look plausible but not fit.