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feat(prefer-mocked): add new rule (jest-community#1470)
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s.v.zaytsev committed Jun 3, 2024
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1 change: 1 addition & 0 deletions README.md
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Expand Up @@ -350,6 +350,7 @@ set to warn in.\
| [prefer-hooks-in-order](docs/rules/prefer-hooks-in-order.md) | Prefer having hooks in a consistent order | | | | |
| [prefer-hooks-on-top](docs/rules/prefer-hooks-on-top.md) | Suggest having hooks before any test cases | | | | |
| [prefer-importing-jest-globals](docs/rules/prefer-importing-jest-globals.md) | Prefer importing Jest globals | | | 🔧 | |
| [prefer-jest-mocked](docs/rules/prefer-jest-mocked.md) | Prefer `jest.mocked()` over `fn as jest.Mock` | | | 🔧 | |
| [prefer-lowercase-title](docs/rules/prefer-lowercase-title.md) | Enforce lowercase test names | | | 🔧 | |
| [prefer-mock-promise-shorthand](docs/rules/prefer-mock-promise-shorthand.md) | Prefer mock resolved/rejected shorthands for promises | | | 🔧 | |
| [prefer-snapshot-hint](docs/rules/prefer-snapshot-hint.md) | Prefer including a hint with external snapshots | | | | |
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38 changes: 38 additions & 0 deletions docs/rules/prefer-jest-mocked.md
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# Prefer `jest.mocked()` over `fn as jest.Mock` (`prefer-jest-mocked`)

🔧 This rule is automatically fixable by the
[`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).

<!-- end auto-generated rule header -->

When working with mocks of functions using Jest, it's recommended to use the
`jest.mocked()` helper function to properly type the mocked functions. This rule
enforces the use of `jest.mocked()` for better type safety and readability.

Restricted types:

- `jest.Mock`
- `jest.MockedFunction`
- `jest.MockedClass`
- `jest.MockedObject`

## Rule details

The following patterns are warnings:

```typescript
(foo as jest.Mock).mockReturnValue(1);
const mock = (foo as jest.Mock).mockReturnValue(1);
(foo as unknown as jest.Mock).mockReturnValue(1);
(Obj.foo as jest.Mock).mockReturnValue(1);
([].foo as jest.Mock).mockReturnValue(1);
```

The following patterns are not warnings:

```js
jest.mocked(foo).mockReturnValue(1);
const mock = jest.mocked(foo).mockReturnValue(1);
jest.mocked(Obj.foo).mockReturnValue(1);
jest.mocked([].foo).mockReturnValue(1);
```
2 changes: 2 additions & 0 deletions src/__tests__/__snapshots__/rules.test.ts.snap
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Expand Up @@ -46,6 +46,7 @@ exports[`rules should export configs that refer to actual rules 1`] = `
"jest/prefer-hooks-in-order": "error",
"jest/prefer-hooks-on-top": "error",
"jest/prefer-importing-jest-globals": "error",
"jest/prefer-jest-mocked": "error",
"jest/prefer-lowercase-title": "error",
"jest/prefer-mock-promise-shorthand": "error",
"jest/prefer-snapshot-hint": "error",
Expand Down Expand Up @@ -128,6 +129,7 @@ exports[`rules should export configs that refer to actual rules 1`] = `
"jest/prefer-hooks-in-order": "error",
"jest/prefer-hooks-on-top": "error",
"jest/prefer-importing-jest-globals": "error",
"jest/prefer-jest-mocked": "error",
"jest/prefer-lowercase-title": "error",
"jest/prefer-mock-promise-shorthand": "error",
"jest/prefer-snapshot-hint": "error",
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2 changes: 1 addition & 1 deletion src/__tests__/rules.test.ts
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Expand Up @@ -2,7 +2,7 @@ import { existsSync } from 'fs';
import { resolve } from 'path';
import plugin from '../';

const numberOfRules = 53;
const numberOfRules = 54;
const ruleNames = Object.keys(plugin.rules);
const deprecatedRules = Object.entries(plugin.rules)
.filter(([, rule]) => rule.meta.deprecated)
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