prefer-to-contain.md

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

💼 This rule is enabled in the following configs: all, style.

🔧 This rule is automatically fixable using the --fix option on the command line.

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

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

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

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

Default configuration

The following patterns are considered warnings:

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:

expect(a).toContain(b);

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