Battle-for-Tismo/tests/trade_graph_test.js

import { TestCase } from "./framework/test_case.js";
import { smallState, cityOf } from "./framework/helpers.js";
import { key } from "../shared/hex.js";

// Places a resource building on a road tile next to `city` and returns its
// coords, so the trade BFS can reach it over the transport network.
function placeReachableMill(state, city, civ = 0) {
  for (const neighbour of state.topology.neighbours(city.coords.x, city.coords.y)) {
    const k = key(neighbour.x, neighbour.y);
    if (!state._isLand(neighbour)) continue;
    if (state.cityAt(neighbour) || state.tileImprovements.has(k)) continue;
    state.tileImprovements.set(k, "steel_mill");
    state.tileImprovementOwner.set(k, civ);
    state.tileImprovementHp.set(k, 1000);
    state._ensureResourceStock(k);
    state.roads.add(k);
    return neighbour;
  }
  return null;
}

export class TradeGraphTest extends TestCase {
  // The graph carries every internal route as an edge, whether or not a delivery
  // ran along it, so the map can draw the idle ones grey.
  test_owned_routes_appear_as_idle_edges() {
    const state = smallState();
    const city = cityOf(state, 0);
    const mill = placeReachableMill(state, city);
    this.assertNotNull(mill, "the fixture found a tile for the mill");

    const graph = state._serializeResourceGraph(0);
    this.assertHas(graph, "edges");
    const hasEdge = graph.edges.some(
      (edge) =>
        edge[0] === mill.x && edge[1] === mill.y &&
        edge[2] === city.coords.x && edge[3] === city.coords.y
    );
    this.assertTrue(hasEdge, "the mill-to-city route is an edge");
    this.assertEmpty(graph.links, "no delivery has run, so no link is active");
    this.assertTrue(
      graph.nodes.some((node) => node[0] === mill.x && node[1] === mill.y),
      "the mill is a storage node"
    );
  }

  // A delivery out of the viewer's own city is an export and belongs on the
  // graph just as an import does, with the foreign buyer drawn as a node.
  test_exports_from_own_nodes_are_kept() {
    const state = smallState();
    const city = cityOf(state, 0);
    const mill = placeReachableMill(state, city);
    const foreign = cityOf(state, 1);
    this.assertNotNull(foreign, "the fixture has a foreign city");
    state.resourceLinks = [{
      from: [mill.x, mill.y],
      to: [foreign.coords.x, foreign.coords.y],
      resource: "steel",
      amount: 12.5,
    }];
    state._resourceGraphCache = null;

    const graph = state._serializeResourceGraph(0);
    const link = graph.links.find(
      (entry) => entry[0] === mill.x && entry[1] === mill.y &&
        entry[2] === foreign.coords.x && entry[3] === foreign.coords.y
    );
    this.assertNotNull(link, "the export is on the graph");
    this.assertEqual(link[4], "steel", "it names the commodity");
    this.assertTrue(
      graph.nodes.some((node) => node[0] === foreign.coords.x && node[1] === foreign.coords.y),
      "the foreign buyer is a node"
    );
  }

  // A delivery into the viewer's own city (an import) still shows, as before.
  test_imports_into_own_cities_are_kept() {
    const state = smallState();
    const city = cityOf(state, 0);
    const foreign = cityOf(state, 1);
    state.resourceLinks = [{
      from: [foreign.coords.x, foreign.coords.y],
      to: [city.coords.x, city.coords.y],
      resource: "food",
      amount: 3,
    }];
    state._resourceGraphCache = null;

    const graph = state._serializeResourceGraph(0);
    this.assertTrue(
      graph.links.some(
        (entry) => entry[2] === city.coords.x && entry[3] === city.coords.y && entry[4] === "food"
      ),
      "the import is on the graph"
    );
  }

  // A spectator gets no graph at all.
  test_a_spectator_sees_no_graph() {
    const state = smallState();
    const graph = state._serializeResourceGraph(-1);
    this.assertEmpty(graph.nodes);
    this.assertEmpty(graph.links);
    this.assertEmpty(graph.edges);
  }

  // The walk is expensive (sea lanes flood the ocean), so it is kept across
  // days until the network changes. Identity proves whether it was reused.
  test_the_trade_walk_is_reused_until_the_network_changes() {
    const state = smallState();
    const city = cityOf(state, 0);
    const nodes = state._resourceNodes();
    const allowSea = state._cityMarketAccess(city);
    const first = state._tradeGraph(city, nodes, allowSea);
    const again = state._tradeGraph(city, nodes, allowSea);
    this.assert(first === again, "an unchanged network reuses the cached walk");

    state._improvementVersion += 1;
    const rebuilt = state._tradeGraph(city, nodes, allowSea);
    this.assert(first !== rebuilt, "a road change throws the cached walk away");
  }

  // A hostile camp can sever a route, so wartime movement drops the walk; in
  // peacetime unit positions never enter it, so a move must not.
  test_a_peacetime_unit_move_keeps_the_trade_walk() {
    const state = smallState();
    const city = cityOf(state, 0);
    const nodes = state._resourceNodes();
    const allowSea = state._cityMarketAccess(city);
    const first = state._tradeGraph(city, nodes, allowSea);

    state._invalidateUnitCaches();
    const afterMove = state._tradeGraph(city, nodes, allowSea);
    this.assert(first === afterMove, "with no war a unit move keeps the walk");

    this.assertTrue(state.requestDeclareWar(0, 1), "the fixture declares a war");
    const atWar = state._tradeGraph(city, nodes, allowSea);
    state._invalidateUnitCaches();
    const atWarAfterMove = state._tradeGraph(city, nodes, allowSea);
    this.assert(atWar !== atWarAfterMove, "in war a unit move drops the walk");
  }
}