test: mock accounts v4 transactions endpoint

[n3ps]

Description

Registers a mock empty Accounts API v4 transactions response for testing.

Part of breaking down the Activity transactions PR into smaller chunks.

Changelog

CHANGELOG entry: null

Related issues

Refs: #29536

Manual testing steps

N/A - test infrastructure mock-only change.

Screenshots/Recordings

N/A - no user-facing UI changes.

Before

N/A

After

N/A

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.

Performance checks (if applicable)

• I've tested on Android
  • N/A - mock-only change.
• I've tested with a power user scenario
  • N/A - mock-only change.
• I've instrumented key operations with Sentry traces for production performance metrics
  • N/A - mock-only change.

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.

  

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[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: SmokeAccounts, SmokeConfirmations, SmokeIdentity, SmokeNetworkAbstractions, SmokeNetworkExpansion, SmokeSwap, SmokeStake, SmokeWalletPlatform, SmokeMoney, SmokePerps, SmokeMultiChainAPI, SmokePredictions, SmokeSeedlessOnboarding, SmokeBrowser, SmokeSnaps
• Selected Performance tags: None (no tests recommended)
• Risk Level: medium
• AI Confidence: 82%

click to see 🤖 AI reasoning details

E2E Test Selection:
The changes modify the global E2E mock server infrastructure (MockServerE2E.ts and mockHelpers.ts), which is used by ALL E2E tests via FixtureHelper.ts. Specifically:

1. A new global default mock is added for the Accounts API v4 transactions endpoint (/v4/multiaccount/transactions), returning an empty response by default.
2. This mock is registered globally during MockServerE2E setup, meaning it applies to every single E2E test run without per-test configuration.

Since MockServerE2E is the central mock server used by all E2E tests, any regression in this infrastructure could break tests across all suites. The change itself is low-risk (adding a defensive empty mock to prevent unmocked network calls), but because it's global infrastructure, it warrants broad validation across all test tags to ensure:

• No existing test that previously relied on the v4 transactions endpoint being unhandled (or proxied) is now broken by the empty mock response
• The mock server still initializes correctly with the new mock registered
• No test that explicitly mocks this endpoint is now conflicting with the global default

All E2E test tags are selected as a conservative approach given the global nature of this infrastructure change.

Performance Test Selection:
These changes are purely in the E2E test infrastructure (mock server setup). They do not affect any app code, UI rendering, data loading, state management, or any other aspect that would impact app performance. No performance tests are needed.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube Cloud