toHaveLength() (prefer-to-have-length)In order to have a better failure message, toHaveLength() should be used upon
asserting expectations on objects length property.
This rule triggers a warning if toBe(), toEqual() or toStrictEqual() is
used to assert objects length property.
expect(files.length).toBe(1);
This rule is enabled by default.
The following patterns are considered warnings:
expect(files.length).toBe(1);
expect(files.length).toEqual(1);
expect(files.length).toStrictEqual(1);
The following pattern is not warning:
expect(files).toHaveLength(1);