Yup validation check if not empty

const validationSchema = Yup.object().shape({
    newPassword: Yup.string().min(8, 'Password must be at least 8 characters');
});

I want to validation check only if newPassword field is not empty. How could I do?

You can use test to do this:

const validationSchema = Yup.object().shape({
    newPassword: Yup.string().test(
        'empty-check',
        'Password must be at least 8 characters',
         password => password.length == 0
    });