Description of the Change

This PR updates the existing behavior of how form fields are displayed on the form. Currently, form fields are shown based on a combination of settings from both Mailchimp and WordPress. If a form field is marked as hidden in Mailchimp, it does not appear on the form, while a visible field can be included in the form based on the settings on the WordPress side.

This PR updates this behavior so that form field visibility is determined solely by the "Include?" option in the WordPress settings, regardless of the Mailchimp settings.

When a new list is set up, hidden fields in Mailchimp will have their "Include?" setting turned off (hidden) by default. Additionally, this PR includes an upgrade script to ensure that forms with hidden fields based on Mailchimp settings do not accidentally start displaying after the update.

Closes #34

How to test the Change

1. Mark a few form fields as hidden in Mailchimp.
2. Go to the Mailchimp settings page in wp-admin, log in to your Mailchimp account, and select an audience list.
3. Verify that hidden fields have their "Include?" setting turned off (checkbox unchecked) by default.
4. Enable the "Include?" option for hidden fields and save the settings.
5. Go to the front end and verify that the form field is now visible.
6. Submit the form with values and confirm that:
   • The form submits successfully.
   • The submitted details are correctly reflected in the Mailchimp contact.

Backward Compatibility

1. For existing users on the trunk branch:
   • Set up the plugin and form.
   • Verify that form fields are hidden based on Mailchimp settings.
2. Update to this PR branch and change the plugin version to 1.7.0 in mailchimp.php by replacing the line with:

   define( 'MCSF_VER', '1.7.0' );

3. Visit the settings page and ensure that all hidden fields have "Include?" turned off and are not visible on the front end.

Changelog Entry

Changed - Make the form field visibility dependent on the WordPress "Include?" settings instead of the Mailchimp settings.

Credits

Props @qasumitbagthariya @dkotter @jeffpaul @MaxwellGarceau @iamdharmesh

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.