[DO NOT MERGE] feat(e2e): replace Mockttp with Go-based mock server by cmd-ob · Pull Request #27904 · MetaMask/metamask-mobile

cmd-ob · 2026-03-25T09:54:31Z

Description

Replaces the Node.js/Mockttp-based E2E mock server with a compiled Go binary for improved performance, reliability, and CI portability.

What changed and why:

Go mock server (tests/mock-server/): A self-contained Go binary that handles proxy interception, URL/body matching, rule storage (thread-safe), request forwarding with port translation, live request tracking, and default mock deserialization. Built for darwin-arm64, darwin-amd64, linux-arm64, linux-amd64.
TypeScript wrapper (tests/api-mocking/GoMockServer.ts): Manages the Go binary lifecycle (start/stop/reset) and exposes the same interface as MockServerE2E so call sites need minimal changes.
MockttpCompat interface (tests/api-mocking/MockttpCompat.ts): A compatibility shim that lets existing test code keep using Mockttp-style .thenReply() / testSpecificMock patterns while the Go server handles the actual interception.
FixtureHelper wired to GoMockServer: FixtureHelper.ts now starts/stops GoMockServer instead of MockServerE2E.
PortManager: New MOCK_SERVER_CONTROL resource type for the Go server's control port.
CI binary freshness check (build.yml): Fails CI if the committed binaries are stale vs the Go source, preventing silent drift.
thenCallback migration deferred: 80 occurrences across 15 files (polymarket 29, ramps 12, perps 11, etc.) are too risky to convert in one PR. The MockttpCompat shim routes thenCallback calls through the existing mockttp layer; each file will be migrated in a domain-specific follow-up.
Swap mocks & analytics tracking fixed for the Go server path.
Account syncing multi-SRP test re-enabled after Go server wiring stabilised it.

Changelog

CHANGELOG entry: null

Related issues

Fixes:

Manual testing steps

Feature: Go mock server E2E infrastructure

  Scenario: E2E tests pass with Go mock server as the interceptor
    Given the Go mock server binaries are built and committed
    When any E2E smoke or regression test runs locally or in CI
    Then the Go binary starts, intercepts HTTP traffic, and returns mocked responses
    And tests that use thenCallback continue to work via the MockttpCompat shim

  Scenario: CI catches stale Go binaries
    Given a developer modifies a .go source file without rebuilding
    When CI runs the binary freshness check
    Then the build fails with a clear message indicating binaries need rebuilding

Screenshots/Recordings

Before

N/A — infrastructure change, no UI impact.

After

N/A — infrastructure change, no UI impact.

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

High Risk
High risk because it replaces core E2E network interception with a new Go proxy/control-plane plus a Node callback bridge, and updates many tests/types to the new MockttpCompat interface; failures could broadly break smoke/regression suites and CI.

Overview
Replaces the E2E mock server implementation: fixtures now start GoMockServer (a spawned Go binary) instead of the previous Node/Mockttp server, and a new MockttpCompat TypeScript shim preserves the existing .forGet/.forPost(...).thenReply/thenJson/thenCallback style APIs.

Adds a Go mock server with a control API and forwarding logic under tests/mock-server/, including rule storage/matching, live-request tracking, and port-translation forwarding; static default mocks are now posted over HTTP instead of passed via a large CLI arg, and dynamic .thenCallback mocks run via a Node “callback bridge” that the Go proxy consults first.

Updates test infra and a few mocks for compatibility: introduces a dedicated control-port allocation (MOCK_SERVER_CONTROL), switches many tests/helpers to type against MockttpCompat, tweaks swap/smart-tx and metametrics mocks to ensure dynamic behavior and request-payload visibility, re-enables the multi-SRP identity smoke test, and adds CI checks to fail when committed mock-server binaries drift from Go sources (plus ignores .worktrees/).

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