test(smart-wallet): avoid O(wallets) storage writes for a new asset

failing test case for #6652

packages/smart-wallet/test/test-addAsset.js

@@ -0,0 +1,87 @@
+// @ts-check
+import { test as anyTest } from '@agoric/zoe/tools/prepare-test-env-ava.js';
+import { E } from '@endo/far';
+import { buildRootObject as buildBankVatRoot } from '@agoric/vats/src/vat-bank.js';
+import { makeIssuerKit } from '@agoric/ertp';
+import { eventLoopIteration } from '@agoric/zoe/tools/eventLoopIteration.js';
+import { makeDefaultTestContext } from './contexts.js';
+import { makeMockTestSpace } from './supports.js';
+
+/** @type {import('ava').TestFn<Awaited<ReturnType<makeDefaultTestContext>>>} */
+const test = anyTest;
+
+const TODO = undefined;
+
+test.before(async t => {
+  const withBankManager = async () => {
+    const bridge = TODO;
+    const bankManager = E(buildBankVatRoot()).makeBankManager(bridge);
+    const noop = () => {};
+    const space0 = await makeMockTestSpace(noop);
+    space0.produce.bankManager.reset();
+    space0.produce.bankManager.resolve(bankManager);
+    return space0;
+  };
+  t.context = await makeDefaultTestContext(t, withBankManager);
+});
+
+const DEBUG = false;
+const bigIntReplacer = (_key, val) =>
+  typeof val === 'bigint' ? Number(val) : val;
+
+const range = qty => [...Array(qty).keys()];
+
+/**
+ * NOTE: this doesn't test all forms of work.
+ * A better test would measure inter-vat messages or some such.
+ */
+test.failing('avoid O(wallets) storage writes for a new asset', async t => {
+  const bankManager = t.context.consume.bankManager;
+
+  let chainStorageWrites = 0;
+
+  const startUser = async ix => {
+    const address = `agoric1u${ix}`;
+    const smartWallet = t.context.simpleProvideWallet(address);
+
+    // stick around waiting for things to happen
+    const current = await E(smartWallet).getCurrentSubscriber();
+    /** @type {bigint | undefined} */
+    let publishCount;
+    for (;;) {
+      // eslint-disable-next-line no-await-in-loop
+      const news = await E(current).subscribeAfter(publishCount);
+      publishCount = news.publishCount;
+      chainStorageWrites += 1;
+      if (DEBUG) {
+        console.log(JSON.stringify(news.head, bigIntReplacer, 2));
+      }
+    }
+  };
+
+  const simulate = async (qty, denom, name) => {
+    range(qty).forEach(startUser);
+    await eventLoopIteration();
+    const initialWrites = chainStorageWrites;
+
+    const kit = makeIssuerKit(name);
+    await E(bankManager).addAsset(denom, name, name, kit);
+    await eventLoopIteration();
+    return {
+      qty,
+      initialWrites,
+      addedWrites: chainStorageWrites - initialWrites,
+    };
+  };
+  const base = await simulate(2, 'ibc/dia1', 'DAI_axl');
+  const exp = await simulate(6, 'ibc/dia2', 'DAI_grv');
+
+  t.log({
+    base: { wallets: base.qty, writes: base.addedWrites },
+    test: { wallets: exp.qty + base.qty, writes: exp.addedWrites },
+  });
+  t.true(
+    exp.addedWrites <= (base.addedWrites * exp.qty) / base.qty / 2,
+    'actual writes should be less than half of linear growth',
+  );
+});