test(bitcoin-wallet-snap): repair the integration suite and cover template output order

[jeremytsng]

Explanation

Stacked on #157, so the base branch is fix/btc-output-reordering-fx-fail — the new test here fails without that fix. Retarget to main once #157 merges.

The problem

The integration suite hasn't run since the migration into this monorepo. Two things stop it before a single test runs: run-integration.sh points at jest.integration.config.js, but the file is jest.integration.config.mjs; and the config has no transform, so it falls back to babel-jest and needs @babel/preset-env, which isn't installed anywhere.

Once it did run, 53 of 60 tests failed. The assertions still expect the old v1 keyring envelope, { pending: false, result }, which the snap stopped returning in 2.0.1. And two tests in keyring.test.ts assume nothing else touches their account, but all four suites share one regtest chain and client-request.test.ts sends 0.001 BTC straight to the address those tests assert on. Which of the two fails depends on the order Jest runs the files in.

Separately, fillPsbt had one assertion: psbt: expect.any(String) // non deterministic. That's why an output-ordering bug was invisible here. Only the change amount varies — the order doesn't.

The fix

Point the script at the real filename, and give the config the same ts-jest transform the unit config already uses.

Update the assertions to the v2 shape. Assert the funding transaction is present rather than alone, and the balance is at least the funded amount rather than exactly it.

Add a test that a template of [deposit, ours(1000), OP_RETURN] comes back with all three in place, ours still worth 1000, and the wallet's change appended after. The existing fillPsbt test now checks output order too — scripts only, since that template's last output belongs to the wallet and legitimately becomes the drain output.

psbt-utils.ts builds and reads PSBTs with no dependencies. Importing @metamask/bitcoindevkit isn't an option here: it wraps a .wasm file that Jest won't resolve.

Verification

Green across repeated runs from a fresh chain: 4 suites, 54 passed, 7 skipped.

The new test was confirmed to fail without #157, coming back as [deposit, OP_RETURN, ours(999778558)] — moved to the end and given the excess.

References

Run it locally with Docker:

yarn workspace @metamask/bitcoin-wallet-snap run build
yarn workspace @metamask/bitcoin-wallet-snap run test:integration

Not addressed here: no CI workflow runs this suite, which is why the rot went unnoticed. Wiring it in needs Docker on the runners, so that's a call for the owning team.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

_{Test-only changes, so there's no changelog entry — the no-changelog label is applied for that reason.}