OpenFrontIO/tests/economy/ConstructionGold.test.ts

import { ConstructionExecution } from "../../src/core/execution/ConstructionExecution";
import { SpawnExecution } from "../../src/core/execution/SpawnExecution";
import {
  Game,
  Player,
  PlayerInfo,
  PlayerType,
  UnitType,
} from "../../src/core/game/Game";
import { setup } from "../util/Setup";

describe("Construction economy", () => {
  let game: Game;
  let player: Player;

  beforeEach(async () => {
    game = await setup("ocean_and_land", {
      infiniteGold: false,
      instantBuild: false,
      infiniteTroops: true,
    });
    const info = new PlayerInfo(
      "builder",
      PlayerType.Human,
      null,
      "builder_id",
    );
    game.addPlayer(info);
    const spawn = game.ref(0, 10);
    game.addExecution(new SpawnExecution(info, spawn));
    while (game.inSpawnPhase()) {
      game.executeNextTick();
    }
    player = game.player(info.id);
  });

  test("City charges gold once and no refund thereafter (allow passive income)", () => {
    const target = game.ref(0, 10);
    const cost = game.unitInfo(UnitType.City).cost(player);
    player.addGold(cost);
    expect(player.gold()).toBe(cost);

    const startTick = game.ticks();
    game.addExecution(new ConstructionExecution(player, UnitType.City, target));

    // First tick usually initializes the execution, second tick performs build and deduction
    game.executeNextTick();
    game.executeNextTick();
    const afterBuild = player.gold();
    const ticksAfterBuild = BigInt(game.ticks() - startTick);
    const passivePerTick = 100n; // DefaultConfig goldAdditionRate for humans
    expect(afterBuild < cost).toBe(true); // cost was deducted
    expect(afterBuild <= ticksAfterBuild * passivePerTick).toBe(true); // only passive income allowed

    // Advance through construction duration
    const duration = game.unitInfo(UnitType.City).constructionDuration ?? 0;
    for (let i = 0; i <= duration + 2; i++) game.executeNextTick();

    const finalGold = player.gold();
    const ticksElapsed = BigInt(game.ticks() - startTick);
    // Ensure no refund equal to cost snuck back in; only passive income accumulated
    expect(finalGold < cost).toBe(true);
    expect(finalGold <= ticksElapsed * passivePerTick).toBe(true);

    // Structure exists and is active
    expect(player.units(UnitType.City)).toHaveLength(1);
    expect(
      (player.units(UnitType.City)[0] as any).isUnderConstruction?.() ?? false,
    ).toBe(false);
  });
});