Schema not allowing blank field when explicitly set as notRequired()

Describe the bug Schema not allowing blank field when explicitly set as notRequired()

To Reproduce Use this code:

const validate = (getValidationSchema) => {
  return (values) => {
    const validationSchema = getValidationSchema(values)
    try {
      validationSchema.validateSync(values, {abortEarly: false})
      return {}
    } catch (error) {
      return getErrorsFromValidationError(error)
    }
  }
}

const validationSchema = function (values) {
  return Yup.object().shape({
    email: Yup.string()
      .email('Invalid email address')
      .when('password', {
        is: (password) => !password || password.length === 0,
        then: Yup.string().email().required(),
        otherwise: Yup.string()
      }),
    password: Yup.string()
      .min(8, `Password has to be at least 8 characters!`)
      .matches(/(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{6,}/, 'Password must contain: numbers, uppercase and lowercase letters\n')
      .notRequired()
      .when('email', {
        is: (email) => !email || email.length === 0,
        then: Yup.string().required(),
        otherwise: Yup.string()
      }),
    confirmPassword: Yup.string()
      .oneOf([values.password], 'Passwords must match'),
  }, [ [ 'email', 'password' ] ])
}

Expected behavior Schema not allowing blank field when explicitly set as notRequired(). Still throwing error about the password field, even though I don’t want to make the user fill in the password field. For example, the user wants to update ONLY their email, or ONLY their password, but not both.

Platform (please complete the following information):

• Browser Chrome
• Version 89.0.4389.90

Additional context

[jakobsandberg]

The validation is failing because an empty string does not pass the regex test in string.matches. You can achieve the desired behavior by passing in excludeEmptyString: true in the options object for string.matches which will skip the evaluation of the regex test.

https://github.com/jquense/yup#stringmatchesregex-regex-options--message-string-excludeemptystring-bool--schema

[ProductOfAmerica]

Any ideas @jakobsandberg