title: Validation accept only two specific fields the selector with yup
body: <p>Whats the best way to allow only two specified values in the selector, for example I have 2 fields for a user to select :</p>
  <ol>
  <li><p>US</p>
  </li>
  <li><p>UGX</p>
  </li>
  </ol>
  <p>below is my code snippet :</p>
  <p>Validations code :</p>
  <pre><code>const signUpSchema = Yup.object().shape({
      countrySelector: Yup.string().required('Please select the country'),
      
  });
  </code></pre>
  <p>JSX snippet</p>
  <pre><code>&lt;Formik
                          validationSchema={signUpSchema}
                          onSubmit={handleSignUpAsync}
                          initialValues={{
                              countrySelector: '',
              
                          }}
                      &gt;
                          &lt;Form&gt;
                              &lt;Field
                                  as=&quot;select&quot;
                                  className=&quot;browser-default custom-select&quot;
                                  name='countrySelector'&gt;
                                  &lt;option value=&quot;-&quot;&gt;-&lt;/option&gt;
                                  &lt;option value=&quot;DE&quot;&gt;DE&lt;/option&gt;
                                  &lt;option value=&quot;US&quot;&gt;US&lt;/option&gt;
                              &lt;/Field&gt;
                          &lt;/Form&gt;
                      &lt;/Formik&gt;
  </code></pre>