test: add lint rule to prevent new snapshot tests (#28582)

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## **Description**

> 
> Prevents new file-based Jest snapshots by enabling
jest/no-restricted-matchers for *.test/*.spec files and explicitly
disallowing toMatchSnapshot() (while still permitting
toMatchInlineSnapshot()).
> 
> Adds a targeted override that turns this restriction off for tests
under **/snaps/** and **/Snaps/**, and includes eslint-plugin-jest as a
new devDependency (lockfile updated accordingly).


## **Changelog**

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CHANGELOG entry:

## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

## **Screenshots/Recordings**

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### **Before**

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### **After**

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## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I've included tests if applicable
- [ ] I've documented my code using [JSDoc](https://jsdoc.app/) format
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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.




<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Adds a new ESLint enforcement that will fail builds for any
remaining/new `toMatchSnapshot()` usage in `*.test`/`*.spec` files,
which could cause unexpected CI failures until all tests comply. Code
changes are otherwise limited to test assertions and dev tooling.
> 
> **Overview**
> **Prevents new file-based Jest snapshots** by enabling
`eslint-plugin-jest` and enforcing `jest/no-restricted-matchers` to
disallow `toMatchSnapshot()` across `*.test`/`*.spec` files, while
explicitly exempting tests under `**/snaps/**` and `**/Snaps/**`.
> 
> Refactors a handful of existing tests (e.g., `BadgeWrapper`, `Main`,
`AssetElement`, `SettingsNotification`, `StyledButton`, `TabCountIcon`,
`Root`) to replace snapshot assertions with targeted
`@testing-library/react-native` queries, and removes the corresponding
snapshot files (including deleting the `TokenImage` snapshot test
entirely).
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
728a801. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: cortisiko

.eslintrc.js

@@ -385,6 +385,33 @@ module.exports = {
         ],
       },
     },
+    {
+      files: ['**/*.test.{js,ts,tsx,jsx}', '**/*.spec.{js,ts,tsx,jsx}'],
+      plugins: ['jest'],
+      rules: {
+        // Prevent new file-based snapshots. Inline snapshots (toMatchInlineSnapshot)
+        // are still allowed as they keep assertions co-located with the test.
+        'jest/no-restricted-matchers': [
+          'error',
+          {
+            toMatchSnapshot:
+              'Use toMatchInlineSnapshot() or an explicit assertion instead. File-based snapshots are being phased out.',
+          },
+        ],
+      },
+    },
+    {
+      // Matches CODEOWNERS `**/snaps/**` and `**/Snaps/**` (@MetaMask/core-platform).
+      // ESLint cannot read CODEOWNERS.
+      files: [
+        '**/snaps/**/*.{test,spec}.{js,ts,tsx,jsx}',
+        '**/Snaps/**/*.{test,spec}.{js,ts,tsx,jsx}',
+      ],
+      plugins: ['jest'],
+      rules: {
+        'jest/no-restricted-matchers': 'off',
+      },
+    },
     // ── Perps controller Core-alignment override ──
     // Enforces the same ESLint rules that Core's @metamask/eslint-config
     // applies to packages/perps-controller so that code written in mobile

app/component-library/components/Badges/BadgeWrapper/BadgeWrapper.test.tsx

@@ -3,16 +3,20 @@ import React from 'react';
 import { render, screen } from '@testing-library/react-native';
 
 // Internal dependencies.
+import { BADGENETWORK_TEST_ID } from '../Badge/variants/BadgeNetwork/BadgeNetwork.constants';
 import BadgeWrapper from './BadgeWrapper';
 import {
   SAMPLE_BADGEWRAPPER_PROPS,
   BADGE_WRAPPER_BADGE_TEST_ID,
 } from './BadgeWrapper.constants';
 
 describe('BadgeWrapper', () => {
-  it('should render BadgeWrapper correctly', () => {
-    const { toJSON } = render(<BadgeWrapper {...SAMPLE_BADGEWRAPPER_PROPS} />);
-    expect(toJSON()).toMatchSnapshot();
-    expect(screen.getByTestId(BADGE_WRAPPER_BADGE_TEST_ID)).toBeDefined();
+  it('renders anchor content, network badge, and wrapper test id', () => {
+    render(<BadgeWrapper {...SAMPLE_BADGEWRAPPER_PROPS} />);
+
+    expect(screen.getByTestId(BADGE_WRAPPER_BADGE_TEST_ID)).toBeOnTheScreen();
+    expect(screen.getByText('C')).toBeOnTheScreen();
+    expect(screen.getByTestId(BADGENETWORK_TEST_ID)).toBeOnTheScreen();
+    expect(screen.getByTestId('network-avatar-image')).toBeOnTheScreen();
   });
 });