Domains: TXT record's value validation is broken

[klimeryk]

• The value is being unnecessarily sanitized (lower case, strip whitespace)
• It's possible to submit an empty value (but the backend thankfully rejects that)

[andrewspittle]

I can confirm this happens in Calypso (and does not happen within the WP Admin Dashboard).

To reproduce:

1. Go to the Domain Management screen.
2. Select a WordPress.com site that has a domain mapped to it.
3. Select the mapped domain name.
4. Click "DNS Records"
5. Click "Add New DNS Record"
6. Select a TXT record.
7. Leave the "Name" field blank.
8. Enter a value in the "Text" field that includes a mix of uppercase and lowercase records. For example, Google's example site verification value: google-site-verification=rXOxyZounnZasA8Z7oaD3c14JdjS9aKSWvsR1EbUSIQ
9. Save the new TXT record.
10. The TXT record will be converted to lowercase.

When attempting the same TXT record addition through WP Admin (via Store > My Domains) the value saves correctly and preserves the upper and lowercase values.

This bug causes validation issues for services like Campaign Monitor that rely on TXT keys with mixed case values. Example.

[klimeryk]

Thanks for additional testing, @andrewspittle! Since this seems like an urgent issue (and I feel guilty, because it was me who introduced this regression 😞), I've created a PR with a fix (#3585). Let me know if it works for you :)

[BrookeDot]

#3585 worked for me in calypso.localhost:3000