wallet-core/packages/taler-wallet-core/src/util/coinSelection.test.ts

/*
 This file is part of GNU Taler
 (C) 2022 Taler Systems S.A.

 GNU Taler is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */
import test, { ExecutionContext } from "ava";
import {
  calculatePlanFormAvailableCoins,
  selectCoinForOperation,
} from "./coinSelection.js";
import {
  AbsoluteTime,
  AgeRestriction,
  AmountJson,
  Amounts,
  Duration,
  TransactionType,
} from "@gnu-taler/taler-util";

function expect(t: ExecutionContext, thing: any): any {
  return {
    deep: {
      equal: (another: any) => t.deepEqual(thing, another),
      equals: (another: any) => t.deepEqual(thing, another),
    },
  };
}

function kudos(v: number): AmountJson {
  return Amounts.fromFloat(v, "KUDOS");
}

function defaultFeeConfig(value: AmountJson, totalAvailable: number) {
  return {
    id: Amounts.stringify(value),
    denomDeposit: kudos(0.01),
    denomRefresh: kudos(0.01),
    denomWithdraw: kudos(0.01),
    duration: Duration.getForever(),
    exchangePurse: undefined,
    exchangeWire: undefined,
    maxAge: AgeRestriction.AGE_UNRESTRICTED,
    totalAvailable,
    value,
  };
}
type Coin = [AmountJson, number];

/**
 * selectCoinForOperation test
 *
 * Test here should check that the correct coins are selected
 */

test("get effective 2", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 5],
    [kudos(5), 5],
  ];
  const result = selectCoinForOperation("credit", kudos(2), "net", {
    list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
    exchanges: {},
  });
  expect(t, result.coins).deep.equal(["KUDOS:2"]);
  t.assert(result.refresh === undefined);
});

test("get raw 4", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 5],
    [kudos(5), 5],
  ];
  const result = selectCoinForOperation("credit", kudos(4), "gross", {
    list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
    exchanges: {},
  });

  expect(t, result.coins).deep.equal(["KUDOS:2", "KUDOS:2"]);
  t.assert(result.refresh === undefined);
});

test("send effective 6", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 5],
    [kudos(5), 5],
  ];
  const result = selectCoinForOperation("debit", kudos(6), "gross", {
    list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
    exchanges: {},
  });

  expect(t, result.coins).deep.equal(["KUDOS:5"]);
  t.assert(result.refresh?.selected === "KUDOS:2");
});

test("send raw 6", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 5],
    [kudos(5), 5],
  ];
  const result = selectCoinForOperation("debit", kudos(6), "gross", {
    list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
    exchanges: {},
  });

  expect(t, result.coins).deep.equal(["KUDOS:5"]);
  t.assert(result.refresh?.selected === "KUDOS:2");
});

test("send raw 20 (not enough)", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 1],
    [kudos(5), 2],
  ];
  const result = selectCoinForOperation("debit", kudos(20), "gross", {
    list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
    exchanges: {},
  });

  expect(t, result.coins).deep.equal(["KUDOS:5", "KUDOS:5", "KUDOS:2"]);
  t.assert(result.refresh === undefined);
});

/**
 * calculatePlanFormAvailableCoins test
 *
 * Test here should check that the plan summary for a transaction is correct
 *  * effective amount
 *  * raw amount
 */

test("deposit effective 2 ", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 1],
    [kudos(5), 2],
  ];
  const result = calculatePlanFormAvailableCoins(
    TransactionType.Deposit,
    kudos(2),
    "effective",
    {
      list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
      exchanges: {
        "2": {
          creditDeadline: AbsoluteTime.never(),
          debitDeadline: AbsoluteTime.never(),
          wireFee: kudos(0.01),
          purseFee: kudos(0.01),
        },
      },
    },
  );

  t.deepEqual(result.rawAmount, "KUDOS:1.98");
  t.deepEqual(result.effectiveAmount, "KUDOS:2");
});

test("deposit raw 2 ", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 1],
    [kudos(5), 2],
  ];
  const result = calculatePlanFormAvailableCoins(
    TransactionType.Deposit,
    kudos(2),
    "raw",
    {
      list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
      exchanges: {
        "2": {
          creditDeadline: AbsoluteTime.never(),
          debitDeadline: AbsoluteTime.never(),
          wireFee: kudos(0.01),
          purseFee: kudos(0.01),
        },
      },
    },
  );

  t.deepEqual(result.rawAmount, "KUDOS:2");
  t.deepEqual(result.effectiveAmount, "KUDOS:2.04");
});

test("withdraw raw 21 ", (t) => {
  const coinList: Coin[] = [
    [kudos(2), 1],
    [kudos(5), 2],
  ];
  const result = calculatePlanFormAvailableCoins(
    TransactionType.Withdrawal,
    kudos(21),
    "raw",
    {
      list: coinList.map(([v, t]) => defaultFeeConfig(v, t)),
      exchanges: {
        "2": {
          creditDeadline: AbsoluteTime.never(),
          debitDeadline: AbsoluteTime.never(),
          wireFee: kudos(0.01),
          purseFee: kudos(0.01),
        },
      },
    },
  );

  // denominations configuration is not suitable
  // for greedy algorithm
  t.deepEqual(result.rawAmount, "KUDOS:20");
  t.deepEqual(result.effectiveAmount, "KUDOS:19.96");
});