source: frontend/node_modules/eslint-plugin-jest/docs/rules/prefer-to-contain.md

# Suggest using `toContain()` (`prefer-to-contain`)

In order to have a better failure message, `toContain()` should be used upon
asserting expectations on an array containing an object.

## Rule details

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

```js
expect(a.includes(b)).toBe(true);
```

```js
expect(a.includes(b)).not.toBe(true);
```

```js
expect(a.includes(b)).toBe(false);
```

### Default configuration

The following patterns are considered warnings:

```js
expect(a.includes(b)).toBe(true);

expect(a.includes(b)).not.toBe(true);

expect(a.includes(b)).toBe(false);

expect(a.includes(b)).toEqual(true);

expect(a.includes(b)).toStrictEqual(true);
```

The following patterns are not considered warnings:

```js
expect(a).toContain(b);

expect(a).not.toContain(b);
```