adrien
71dad18e8d
Central banks now redeem the national money foreign banks hold, sell reserves to defend a weak rate, and cover part of strategic imports from reserves. Five repeatable technologies raise each commodity's output per unit of energy. Hostile troops on a road or sea lane sever trade, power and unit supply. Middlemen buy food to resell to neighbours at a markup, and starving regions buy before those topping up their buffers, which clears the landlocked famines. The economic map's trade graph gains a colour legend.
93 lines
3.8 KiB
JavaScript
93 lines
3.8 KiB
JavaScript
import { TestCase } from "./framework/test_case.js";
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import { smallState, cityOf } from "./framework/helpers.js";
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import { MONEY } from "../shared/data.js";
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// Gives both central banks a symmetric reserve of each other's currency and the
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// matching issued-currency debt, so the FX desk has something to work.
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function bookReserves(state, amount = 1000) {
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const a = state.currencyOf(0).code;
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const b = state.currencyOf(1).code;
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state._addReserve(1, a, amount);
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state._addReserve(0, b, amount);
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state._addCentralBankDebt(0, a, amount);
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state._addCentralBankDebt(1, b, amount);
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return { a, b };
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}
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export class CentralBankFxTest extends TestCase {
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test_redeeming_own_currency_retires_it_from_the_foreign_bank() {
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const state = smallState();
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const { a, b } = bookReserves(state, 1000);
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const redeemed = state._redeemOwnCurrency(0, 500);
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this.assertApprox(redeemed, 500);
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// Britain hands back the francs it held; France hands back the pounds.
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this.assertApprox(state.getCentralBankReserves(1).get(a), 500);
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this.assertApprox(state.getCentralBankReserves(0).get(b), 500);
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// Both issued-currency liabilities shrink with the money retired.
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this.assertApprox(state.getCentralBankDebt(0).get(a), 500);
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this.assertApprox(state.getCentralBankDebt(1).get(b), 500);
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// The bid for francs and the offer of pounds register as currency demand.
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this.assertGreater(state._currencyDemand.get(0) || 0, 0);
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this.assertLess(state._currencyDemand.get(1) || 0, 0);
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}
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test_a_weak_rate_sells_more_reserves_than_a_strong_one() {
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const strong = smallState();
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bookReserves(strong, 1_000_000);
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strong.setCurrencyValue(0, 1);
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const ordinary = strong._settleCentralBankFx(0);
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const weak = smallState();
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bookReserves(weak, 1_000_000);
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weak.setCurrencyValue(0, 0.9);
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const defended = weak._settleCentralBankFx(0);
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this.assertGreater(ordinary, 0, "the bank redeems even when the rate is calm");
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this.assertGreater(defended, ordinary, "a weak rate is defended harder");
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}
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test_the_bank_leaves_its_reserves_alone_without_money_held_abroad() {
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const state = smallState();
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const b = state.currencyOf(1).code;
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state._addReserve(0, b, 1_000_000);
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this.assertApprox(state._settleCentralBankFx(0), 0);
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}
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test_the_import_subsidy_draws_on_its_own_currency_reserves() {
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const state = smallState();
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const buyer = cityOf(state, 0);
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const a = state.currencyOf(0).code;
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const b = state.currencyOf(1).code;
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state._addReserve(0, b, 1_000_000);
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const before = state.getRegionCash(buyer).get(a) || 0;
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const acquired = state._regionAcquireCurrency(buyer, 1, 1000, null, true, 400);
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this.assertApprox(acquired.subsidised, 400, 1e-6, "the bank covered its share");
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this.assertApprox(acquired.amount, 1000, 1e-6, "the seller is paid in full");
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this.assertApprox(
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state.getCentralBankReserves(0).get(b), 999_600, 1e-6,
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"the subsidy came out of reserves"
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);
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const after = state.getRegionCash(buyer).get(a) || 0;
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this.assertApprox(before - after, 600, 1e-6, "the buyer paid only the rest");
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}
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test_the_import_subsidy_budget_is_capped_for_the_day() {
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const state = smallState();
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const b = state.currencyOf(1).code;
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state._addReserve(0, b, 1_000_000);
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state._fxSubsidySpent = new Map();
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const budget = 1_000_000 * MONEY.fx.importSubsidyPerDay;
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const first = state._centralBankImportSubsidy(0, "food", 1_000_000);
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this.assertApprox(first, budget, 1e-6);
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state._recordImportSubsidy(0, first);
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this.assertApprox(state._centralBankImportSubsidy(0, "food", 1_000_000), 0);
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}
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test_no_subsidy_for_a_resource_the_bank_does_not_back() {
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const state = smallState();
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const b = state.currencyOf(1).code;
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state._addReserve(0, b, 1_000_000);
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this.assertEqual(state._centralBankImportSubsidy(0, "luxury", 1_000_000), 0);
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}
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}
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