fix(e2e): add default mock for single-token metadata API endpoint

[dylanbutler1]

Description

The trade-ios-smoke-1 job has been failing this week across bridge, swap, gasless swap, and deeplink tests with:

Test made 2 unmocked request(s) (2 unique):
1. [GET] https://token.api.cx.metamask.io/token/1?address=0xacA92E438df0B2401fF60dA7E4337B687a2435DA&includeRwaData=true
2. [GET] https://token.api.cx.metamask.io/token/59144?address=0xacA92E438df0B2401fF60dA7E4337B687a2435DA&includeRwaData=true

Root cause: The default E2E mocks in token-apis.ts cover /tokens/{chainId} (plural — token lists), /assets? (v2), and tokens.api.../v3/assets (v3), but not /token/{chainId}?address=... (singular — single-token metadata). This endpoint is called by the token controller whenever the app encounters a token (swap quotes, bridge destinations, etc.). It was only mocked in per-test setups for specific addresses (mUSD conversion, perps, polymarket), so any test hitting a different token/chain combo triggered validateLiveRequests() failure.

The address 0xacA92E438df0B2401fF60dA7E4337B687a2435DA is the mUSD token on Ethereum (chain 1) and Linea (chain 59144).

Fix: Add a default catch-all regex mock for /token/{chainId}?address=0x... that returns a minimal valid token metadata response. Per-test mocks with higher specificity still take precedence.

Changelog

CHANGELOG entry: null

Related issues

Refs: #26568

Manual testing steps

Feature: Trade smoke E2E reliability

  Scenario: swap/bridge/gasless tests no longer fail on unmocked token metadata
    Given a CI environment running trade-ios-smoke-1

    When bridge-action-smoke, swap-action-smoke, gasless-swap, or
         swap-deeplink-smoke tests make token metadata API requests
    Then the requests are caught by the default mock
    And validateLiveRequests() does not throw

Screenshots/Recordings

N/A — no UI changes, E2E test infrastructure only.

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.

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.

Made with Cursor

---

Note

Low Risk
Test-only mocking change; main risk is a too-broad regex masking missing per-test mocks or affecting tests that expect real token metadata.

Overview
Adds a default GET mock for the Token API single-token metadata endpoint (/token/{chainId}?address=0x...) in tests/api-mocking/mock-responses/defaults/token-apis.ts, matching requests via a new regex.

The mock returns a minimal token metadata payload (address/symbol/decimals/name/iconUrl, etc.) so E2E runs don’t fail validateLiveRequests() when tests encounter previously-unmocked tokens/chains.

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[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: SmokeTrade, SmokeConfirmations, SmokeNetworkAbstractions, SmokeNetworkExpansion, SmokeMultiChainAPI
• Selected Performance tags: None (no tests recommended)
• Risk Level: medium
• AI Confidence: 82%

click to see 🤖 AI reasoning details

E2E Test Selection:
The change adds a new default mock for the single-token metadata API endpoint (/token/{chainId}?address=0x...) to the global test mock defaults in tests/api-mocking/mock-responses/defaults/token-apis.ts.

Nature of the change:

• Adds a regex-based default mock for https://token.api.cx.metamask.io/token/{chainId}?address=0x...
• Returns a minimal valid token metadata response to prevent validateLiveRequests failures
• This is a global default mock used across ALL E2E tests via DEFAULT_MOCKS in index.ts
• The change is additive (no existing mocks modified)

Why these tags:

• SmokeTrade: Swap and bridge flows are explicitly mentioned in the comment as triggers for this endpoint ("swap quotes, bridge destinations"). These tests are most likely to exercise the single-token metadata endpoint.
• SmokeConfirmations: Token approval and ERC-20 transaction flows fetch token metadata. Also required as a dependent tag when SmokeTrade is selected.
• SmokeNetworkAbstractions: Multi-chain token filtering and network-specific token operations fetch token metadata.
• SmokeNetworkExpansion: Multi-chain provider and Solana token flows may trigger token metadata requests.
• SmokeMultiChainAPI: Session-based multi-chain permissions involve token operations across chains.

Why not all tags:

• The change is a defensive mock addition that prevents failures rather than changing behavior. Tests that don't involve token metadata fetches (SmokeAccounts, SmokeIdentity, SmokeRamps, SmokeCard, SmokePerps, SmokePredictions, SmokeWalletPlatform, FlaskBuildTests) are unlikely to be affected by this specific mock addition.
• The risk is that the new mock could interfere with test-specific mocks that override the default, but since it's additive and uses a specific regex pattern, this is unlikely.

Performance tests: No performance impact expected from a test mock change.

Performance Test Selection:
This is a test infrastructure change (adding a default API mock) with no impact on app code or runtime 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

[github-actions]

✅ E2E Fixture Validation — Schema is up to date
17 value mismatches detected (expected — fixture represents an existing user).
View details