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## **Description**

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Write a short description of the changes included in this pull request,
also include relevant motivation and context. Have in mind the following
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1. What is the reason for the change?
2. What is the improvement/solution?
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This patches an issue in `add-contact.component.js` where the disabled
state of the `Save` button would disappear only after a successful ENS
resolution, effectively preventing plain addresses to be entered.
I also added some extra unit tests to check for some of the cases that
weren't covered before.

[![Open in GitHub
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## **Related issues**

fixes #25918
fixes #25889

## **Manual testing steps**

1. Go to Settings > Contacts > Add Contact
2. Enter a name and a valid Ethereum address
3. Observe the Save button getting enabled
4. Edit the address to make it invalid, observe the Save button getting
disabled
5. Instead of an address, enter an ENS name and pick the resolved result
6. Observe the Save button getting enabled
7. Observe that the input is still editable (repeat 4.)

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**

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## **Pre-merge author checklist**

- [X] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [X] I've completed the PR template to the best of my ability
- [X] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

---------

Signed-off-by: Mircea Nistor <mirceanis@gmail.com>