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.
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);
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);