fix: MUSD-225 Update "Get mUSD" CTA to respect network filter when creating mUSD conversion tx

[Matt561]

Description

Updated "Get mUSD" CTA to respect network filter when creating mUSD conversion tx. If no supported asset exists on the selected network, we fallback to the first available.

Previously, we ignored the network filter and always selected the first eligible token even if it was on another network.

Changelog

CHANGELOG entry: updated get mUSD cta to respect network filter when creating mUSD conversion tx

Related issues

Fixes: MUSD-225: Buy/Get CTA doesn't take selected chain into account when pre-selecting output chain and payment token

Manual testing steps

Feature: mUSD conversion respects selected network filter

  Scenario: user initiates mUSD conversion with a selected network filter
    Given the user has eligible conversion tokens on multiple networks
    And the user has filtered their asset list to a specific network

    When the user taps "Get mUSD"
    Then the app uses a payment token on the selected network when one is available
    And the conversion output network matches the chosen payment token network

  Scenario: user initiates mUSD conversion when selected network has no eligible token
    Given the user has eligible conversion tokens
    And the user has filtered their asset list to a network with no eligible token

    When the user taps "Get mUSD"
    Then the app falls back to the first available eligible token
    And the conversion output network matches the fallback token network

Screenshots/Recordings

Before

First eligible token on any chain was selected

After

First eligible token on selected network selected. Falls back to first eligible on any network if user's selected network doesn't have eligible tokens.

Pre-merge author checklist

• I’ve followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• 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 format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). 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.

---

Note

Aligns mUSD conversion to the selected network when available, improving token/chain preselection.

• Updates MusdConversionAssetListCta to pick preferredPaymentToken from selectedChainId (falls back to tokens[0]) and sets outputChainId via getMusdOutputChainId(paymentToken.chainId)
• Normalizes addresses and chain IDs using toChecksumAddress and toHex
• Adds tests covering selected-network token usage, fallback behavior, and preserves existing CTA/telemetry behaviors

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🔍 Smart E2E Test Selection

• Selected E2E tags: None (no tests recommended)
• Risk Level: low
• AI Confidence: 85%

click to see 🤖 AI reasoning details

The changes are limited to the MusdConversionAssetListCta component in the Earn/Musd feature. The code change improves token selection logic to respect network filters when initiating mUSD conversion - preferring tokens from the selected chain if available, otherwise falling back to the first token.

Key observations:

1. The changes are isolated to a specific feature component (mUSD conversion CTA)
2. Two comprehensive unit tests were added to cover the new logic
3. No E2E tests exist for mUSD or Earn features in the codebase
4. The component is used in the Tokens list view but the change doesn't affect core wallet functionality
5. The logic change is straightforward and well-tested at the unit level

Since there are no E2E tests for this feature and the changes are well-covered by unit tests, running E2E tests would not provide additional coverage for these specific changes. The risk is low as this is a localized UI component change with proper test coverage.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
90.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud