migrate-to-shoehorn

1# 迁移到 Shoehorn
2 
3## 为什么用 shoehorn？
4 
5`shoehorn` 允许你在 tests 中传入 partial data，同时保持 TypeScript 满意。它用 type-safe alternatives 替换 `as` assertions。
6 
7**只用于 test code。** 永远不要在 production code 中使用 shoehorn。
8 
9Tests 中 `as` 的问题：
10 
11- 经过训练，不去使用它
12- 必须手动指定 target type
13- 对故意错误的数据需要 double-as（`as unknown as Type`）
14 
15## 安装
16 
17```bash
18npm i @total-typescript/shoehorn
19```
20 
21## 迁移模式
22 
23### 只需要少数属性的大型 objects
24 
25Before:
26 
27```ts
28type Request = {
29  body: { id: string };
30  headers: Record<string, string>;
31  cookies: Record<string, string>;
32  // ...20 more properties
33};
34 
35it("gets user by id", () => {
36  // Only care about body.id but must fake entire Request
37  getUser({
38    body: { id: "123" },
39    headers: {},
40    cookies: {},
41    // ...fake all 20 properties
42  });
43});
44```
45 
46After:
47 
48```ts
49import { fromPartial } from "@total-typescript/shoehorn";
50 
51it("gets user by id", () => {
52  getUser(
53    fromPartial({
54      body: { id: "123" },
55    }),
56  );
57});
58```
59 
60### `as Type` → `fromPartial()`
61 
62Before:
63 
64```ts
65getUser({ body: { id: "123" } } as Request);
66```
67 
68After:
69 
70```ts
71import { fromPartial } from "@total-typescript/shoehorn";
72 
73getUser(fromPartial({ body: { id: "123" } }));
74```
75 
76### `as unknown as Type` → `fromAny()`
77 
78Before:
79 
80```ts
81getUser({ body: { id: 123 } } as unknown as Request); // wrong type on purpose
82```
83 
84After:
85 
86```ts
87import { fromAny } from "@total-typescript/shoehorn";
88 
89getUser(fromAny({ body: { id: 123 } }));
90```
91 
92## 何时使用哪一个
93 
94| Function        | Use case                                           |
95…