Yup schema validation password and confirmPassword doesn't work

Try this out:

import * as Yup from 'yup';

validationSchema: Yup.object({
  password: Yup.string().required('Password is required'),
  passwordConfirmation: Yup.string()
     .oneOf([Yup.ref('password'), null], 'Passwords must match')
});

Based on @anoNewb answer and the request made by @Renan,

Yup.object({
  password: Yup.string().required('Password is required'),
  passwordConfirmation: Yup.string()
    .test('passwords-match', 'Passwords must match', function(value){
      return this.parent.password === value
    })
})