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.
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 a warning:
expect(files).toHaveLength(1)