feat(localchain): add withdraw facet to localChainAccount

packages/vats/src/localchain.js

@@ -1,17 +1,17 @@
 // @ts-check
 import { E } from '@endo/far';
 import { M } from '@endo/patterns';
-import { AmountShape } from '@agoric/ertp';
+import { AmountShape, PaymentShape } from '@agoric/ertp';
 
 const { Fail } = assert;
 
 /**
+ * @import {Amount, Payment} from '@agoric/ertp/exported.js';
+ * @import {TypedJson, ResponseTo} from '@agoric/cosmic-proto';
  * @import {BankManager, Bank} from './vat-bank.js';
  * @import {ScopedBridgeManager} from './types.js';
  */
 
-/** @import {TypedJson, ResponseTo} from '@agoric/cosmic-proto'; */
-
 /**
  * @typedef {{
  *   system: ScopedBridgeManager;
@@ -28,9 +28,8 @@ const { Fail } = assert;
 
 export const LocalChainAccountI = M.interface('LocalChainAccount', {
   getAddress: M.callWhen().returns(M.string()),
-  deposit: M.callWhen(M.remotable('Payment'))
-    .optional(M.pattern())
-    .returns(AmountShape),
+  deposit: M.callWhen(PaymentShape).returns(AmountShape),
+  withdraw: M.callWhen(AmountShape).returns(PaymentShape),
   executeTx: M.callWhen(M.arrayOf(M.record())).returns(M.arrayOf(M.record())),
 });
 
@@ -54,7 +53,8 @@ const prepareLocalChainAccount = zone =>
        * This is safe, since even if the payment lies about its brand, ERTP will
        * reject spoofed payment objects when depositing into a purse.
        *
-       * @param {Payment} payment
+       * @param {Payment<'nat'>} payment
+       * @returns {Promise<Amount>}
        */
       async deposit(payment) {
         const { bank } = this.state;
@@ -63,6 +63,18 @@ const prepareLocalChainAccount = zone =>
         const purse = E(bank).getPurse(allegedBrand);
         return E(purse).deposit(payment);
       },
+      /**
+       * Withdraw a payment from the account's bank purse that matches the
+       * alleged brand.
+       *
+       * @param {Amount<'nat'>} amount
+       * @returns {Promise<Payment>} payment
+       */
+      async withdraw(amount) {
+        const { bank } = this.state;
+        const purse = E(bank).getPurse(amount.brand);
+        return E(purse).withdraw(amount);
+      },
       /**
        * Execute a batch of transactions and return the responses. Use
        * `typedJson()` on the arguments to get typed return values.

packages/vats/test/localchain.test.js

@@ -3,6 +3,7 @@ import { reincarnate } from '@agoric/swingset-liveslots/tools/setup-vat-data.js'
 import { E } from '@endo/far';
 import { M, matches } from '@endo/patterns';
 import { makeDurableZone } from '@agoric/zone/durable.js';
+import { AmountMath, AssetKind, makeIssuerKit } from '@agoric/ertp';
 import { buildRootObject } from '../src/vat-bank.js';
 import { prepareLocalChainTools } from '../src/localchain.js';
 
@@ -36,6 +37,18 @@ const makeTestContext = async t => {
           ret = 'agoricfoo';
           break;
         }
+        case 'VBANK_GET_BALANCE': {
+          const { address, denom, type: _type, ...rest } = obj;
+          t.is(address, 'agoricfoo');
+          t.deepEqual(rest, {});
+          if (denom === 'ubld') {
+            ret = '100000000';
+          } else {
+            t.fail(`unrecognized denomination ${denom}`);
+          }
+          break;
+        }
+
         default: {
           t.is(obj, null);
         }
@@ -58,6 +71,21 @@ const makeTestContext = async t => {
     bankManager,
   };
   const localchain = makeLocalChain(powers);
+  const bldIssuerKit = makeIssuerKit(
+    'BLD',
+    AssetKind.NAT,
+    harden({ decimalPlaces: 6 }),
+  );
+
+  const oneHundredBldAmt = AmountMath.make(bldIssuerKit.brand, 100_000_000n);
+  const oneHundredBldPmt = bldIssuerKit.mint.mintPayment(oneHundredBldAmt);
+
+  const beanIssuerKit = makeIssuerKit(
+    'BEAN',
+    AssetKind.NAT,
+    harden({ decimalPlaces: 6 }),
+  );
+  const oneHundredBeanAmt = AmountMath.make(beanIssuerKit.brand, 100_000_000n);
 
   return {
     baggage,
@@ -67,6 +95,11 @@ const makeTestContext = async t => {
     bankVat,
     bankManager,
     localchain,
+    bldIssuerKit,
+    bldIssuer: bldIssuerKit.issuer,
+    oneHundredBldPmt,
+    oneHundredBldAmt,
+    oneHundredBeanAmt,
   };
 };
 
@@ -75,11 +108,49 @@ test.beforeEach(t => {
 });
 
 test('localchain - deposit and withdraw', async t => {
-  const { localchain } = await t.context;
+  const user = async () => {
+    const { localchain } = await t.context;
+    const lca = await E(localchain).makeAccount();
+    t.true(matches(lca, M.remotable('LocalChainAccount')));
 
-  const lca = await E(localchain).makeAccount();
-  t.true(matches(lca, M.remotable('LocalChainAccount')));
+    const address = await E(lca).getAddress();
+    t.is(address, 'agoricfoo');
+    return { lca };
+  };
+  const { lca } = await user();
 
-  const address = await E(lca).getAddress();
-  t.is(address, 'agoricfoo');
+  const gov = async () => {
+    const { bankManager, bldIssuerKit } = await t.context;
+    await t.notThrowsAsync(
+      E(bankManager).addAsset('ubld', 'BLD', 'Staking Token', bldIssuerKit),
+    );
+  };
+  await gov();
+
+  /** @param {import('../src/localchain.js').LocalChainAccount} usersLca */
+  const userDeposit = async usersLca => {
+    const { oneHundredBldPmt, oneHundredBldAmt } = await t.context;
+    const res = await E(usersLca).deposit(oneHundredBldPmt);
+    t.deepEqual(
+      res,
+      oneHundredBldAmt,
+      'deposit returns description of payment',
+    );
+  };
+  await userDeposit(lca);
+
+  /** @param {import('../src/localchain.js').LocalChainAccount} usersLca */
+  const userWithdraw = async usersLca => {
+    const { oneHundredBldAmt, bldIssuer, oneHundredBeanAmt } = await t.context;
+
+    const payment = await E(usersLca).withdraw(oneHundredBldAmt);
+    // @ts-expect-error Argument of type 'Payment' is not assignable to parameter of type 'ERef<Payment<"nat", any>>'.
+    const paymentAmount = await E(bldIssuer).getAmountOf(payment);
+    t.deepEqual(paymentAmount, oneHundredBldAmt, 'withdraw returns a payment');
+
+    await t.throwsAsync(() => E(usersLca).withdraw(oneHundredBeanAmt), {
+      message: /not found in collection "brandToAssetRecord"/,
+    });
+  };
+  await userWithdraw(lca);
 });