# vitest/prefer-to-contain

📝 Enforce using toContain().

⚠️ This rule _warns_ in the 🌐 `all` config.

🔧 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 -->

This rule triggers a warning if `toBe()`, `toEqual()` or `toStrickEqual()` is used to assert object inclusion in an array.

The following patterns are considered warnings:

```ts
expect(a.includes(b)).toBe(true)
expect(a.includes(b)).toEqual(true)
expect(a.includes(b)).toStrictEqual(true)
```

The following patterns are not considered warnings:

```ts
expect(a).toContain(b)
```