Yup conditional validation

schema.js

Yup.object().shape({
  email: Yup.string().email('Invalid email address').required('Email is required!'),
  username: Yup.string().required('This man needs a username').when('email', (email, schema) => {
    if (email === 'foobar@example.com') { return schema.min(10); }
    return schema;
  }),
});