[ulissesferreira]

Summary

Adds the full @metamask/snaps-vitest implementation on top of #4174. It is a Vitest port of @metamask/snaps-jest, with the same end-to-end testing API.

src/
├── environment.ts       # Vitest environment: starts server, exposes installSnap
├── setup.ts             # registers matchers
├── matchers.ts          # toRespondWith, toRender, toSendNotification, ...
├── helpers.ts           # installSnap, getMockAccount, getStateFrom* helpers
├── options.ts           # environmentOptions validation
├── global.ts            # `expect` type augmentation (@vitest/expect)
├── internals/           # server, logger, account helpers
└── test-utils/          # test-only helpers and fixture Snap

test/
└── e2e.test.ts          # installSnap + matcher smoke test

compat (not committed)
└── Bitcoin and Solana suites from internal-snaps, run against the built dist

Key adaptation to this monorepo:

• Uses workspace snaps-controllers, snaps-sdk, snaps-simulation, and snaps-utils.
• Uses Vitest ^3.1.1, matching the version already installed here, and the Vitest 3 environment API (transformMode).
• Configures Snap JSX through Vite esbuild (jsx: 'automatic', jsxDev: false), matching the production Snaps runtime.
• Uses @metamask/snaps-utils/test-utils instead of the vendored test-utils shim used in the standalone project.
• Matcher types augment Vitest's Assertion and AsymmetricMatchersContaining interfaces.

Evidence

• Before: feat(snaps-vitest): scaffold package #4174 contains only the package scaffold and config helper.
  After:
  • yarn workspace @metamask/snaps-vitest run build, lint, and test pass.
  • Package suite: 106 passed (9 files).
  • Consumer smoke test using the built getSnapsVitestConfig + packed dist: 1 passed.
  • Bitcoin internal-snaps integration suite against the built package (fresh regtest chain): 53 passed / 7 skipped, matching the Jest baseline.
  • Solana tests importing snaps-jest (4 files) against the built package: 15 passed / 1 skipped, matching the Jest baseline.

Merge Danger

Door: two-way

Blast Radius: low

New package only; the shared-file wiring is in #4174. Merge #4174 first.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (feat/snaps-vitest-package@7ee7176). Learn more about missing BASE report.

Additional details and impacted files

@@                     Coverage Diff                      @@
##             feat/snaps-vitest-package    #4175   +/-   ##
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  Coverage                             ?   98.69%           
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  Files                                ?      429           
  Lines                                ?    12533           
  Branches                             ?     1986           
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  Hits                                 ?    12369           
  Misses                               ?      164           
  Partials                             ?        0           

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