Initial commit
This commit is contained in:
Jesse
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/**
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* Build order step 2 — "Move legality provable against Appendix A's worked switching examples."
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* See architecture/components.md §4.
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*/
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import { describe, it } from 'node:test';
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import assert from 'node:assert/strict';
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import type {
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GridCoord,
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OfficeArea,
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RollingStock,
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TrackCard,
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TurnoutOrientation,
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} from '../src/engine/state.ts';
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import { coordKey } from '../src/engine/state.ts';
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import type { MoveContext, Occupancy, Port } from '../src/engine/track.ts';
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import {
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allReachable,
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canDropCarsAt,
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canPlaceAt,
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exitsFrom,
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hasPort,
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neighbour,
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opposite,
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reachableDestinations,
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} from '../src/engine/track.ts';
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// ---------------------------------------------------------------------------
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// Fixture helpers
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// ---------------------------------------------------------------------------
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const straight = (standing: RollingStock[] = []): TrackCard => ({
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geometry: { kind: 'track', geometry: 'straight' },
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baseOperationalRail: true,
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standing,
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facility: null,
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modifiers: [],
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});
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/** A straight rotated to run north-south. Needed to meet the Office's junction stubs (Gap 11). */
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const nsStraight = (standing: RollingStock[] = []): TrackCard => ({
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geometry: { kind: 'track', geometry: 'straight', axis: 'ns' },
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baseOperationalRail: true,
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standing,
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facility: null,
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modifiers: [],
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});
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const turnout = (o?: TurnoutOrientation): TrackCard => ({
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geometry: o
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? { kind: 'track', geometry: 'turnout', turnout: o }
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: { kind: 'track', geometry: 'turnout' },
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baseOperationalRail: false, // no wheel icon — a train may pass through but not stop (§A.1)
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standing: [],
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facility: null,
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modifiers: [],
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});
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const officeCard = (): TrackCard => ({
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geometry: { kind: 'office' },
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baseOperationalRail: true,
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standing: [],
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facility: null,
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modifiers: [],
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});
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const lockedFacility = (): TrackCard => ({
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geometry: { kind: 'facility', facility: 'mineTipple' },
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baseOperationalRail: true,
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standing: [],
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// A load sitting on MEN|AT|WORK locks the industry track down (§9.3).
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facility: {
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kind: 'freight',
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subtype: 'mineTipple',
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allows: { outbound: true, inbound: false },
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outboundBox: [],
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inboundBox: [],
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capacity: { outbound: 3, inbound: 0 },
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menAtWork: [{ type: 'hopper', dir: 'out' }, null, null],
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industryTrack: { length: 4, cars: [] },
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laborers: 3,
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porters: 0,
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usedThisStage: { laborers: 0, porters: 0 },
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},
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modifiers: [],
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});
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const car = (): RollingStock => ({ type: 'boxcar', loaded: false });
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function areaFrom(cards: Record<string, TrackCard>, officeCoord: GridCoord): OfficeArea {
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const grid = new Map<string, TrackCard>();
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for (const [k, v] of Object.entries(cards)) grid.set(k, v);
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return {
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owner: 0,
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tier: 'whistlePost',
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grid,
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officeCoord,
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runningRow: officeCoord.row,
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limitsWest: { row: officeCoord.row, col: officeCoord.col - 2 },
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limitsEast: { row: officeCoord.row, col: officeCoord.col + 2 },
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adOccupancy: [],
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};
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}
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const emptyOccupancy: Occupancy = { trayAt: () => null, freeAdTracks: () => 1 };
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function ctxFor(area: OfficeArea, over: Partial<MoveContext> = {}): MoveContext {
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return { area, occupancy: emptyOccupancy, consistSize: 0, self: 'tray0', ...over };
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}
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const at = (r: number, c: number): GridCoord => ({ row: r, col: c });
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const has = (dests: { coord: GridCoord }[], r: number, c: number): boolean =>
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dests.some((d) => d.coord.row === r && d.coord.col === c);
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// ---------------------------------------------------------------------------
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describe('ports and geometry', () => {
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it('pairs opposite ports and grid neighbours consistently', () => {
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for (const p of ['n', 's', 'e', 'w'] as Port[]) {
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assert.equal(opposite(opposite(p)), p);
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const there = neighbour(at(0, 0), p);
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const back = neighbour(there, opposite(p));
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assert.deepEqual(back, at(0, 0));
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}
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});
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it('joins a turnout stem to both legs but never the legs to each other', () => {
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// §A.1 — the whole point. Entering from the stem reaches either leg; entering from a leg
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// reaches only the stem. This is an ABSENT edge, not a one-way edge.
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const t = turnout({ stem: 'e', through: 'w', diverge: 'n' });
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assert.deepEqual(exitsFrom(t, 'e').sort(), ['n', 'w']);
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assert.deepEqual(exitsFrom(t, 'w'), ['e']);
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assert.deepEqual(exitsFrom(t, 'n'), ['e']);
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});
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it('lets a train traverse a turnout in both directions', () => {
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// A→B and B→A are both legal; only B↔C is missing.
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const t = turnout({ stem: 'e', through: 'w', diverge: 'n' });
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assert.ok(exitsFrom(t, 'e').includes('n'), 'stem to diverging leg');
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assert.ok(exitsFrom(t, 'n').includes('e'), 'diverging leg back to stem');
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});
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it('gives the Office card junction stubs above and below', () => {
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// Gap 8 — plain junctions, so unlike a turnout no pair is missing between track and stub.
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const o = officeCard();
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for (const p of ['n', 's', 'e', 'w'] as Port[]) assert.ok(hasPort(o, p), `office port ${p}`);
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assert.ok(exitsFrom(o, 'n').includes('e'));
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assert.ok(exitsFrom(o, 'n').includes('w'));
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assert.ok(!exitsFrom(o, 'n').includes('s'), 'north must not cross to south');
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});
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it('gives a run-around both ends of the loop', () => {
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// §A.5's facing-point move is impossible without one.
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const r: TrackCard = {
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geometry: { kind: 'track', geometry: 'runAround' },
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baseOperationalRail: true,
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standing: [],
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facility: null,
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modifiers: [],
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};
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assert.deepEqual(exitsFrom(r, 'n').sort(), ['e', 'w']);
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});
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});
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// ---------------------------------------------------------------------------
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describe('Move legality', () => {
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// row 1: [B n-s straight] <- must have a SOUTH port to meet the Office stub
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// row 0: [D] [E office ] [F]
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const basicArea = (): OfficeArea =>
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areaFrom(
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{
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[coordKey(at(0, -1))]: straight(),
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[coordKey(at(0, 0))]: officeCard(),
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[coordKey(at(0, 1))]: straight(),
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[coordKey(at(1, 0))]: nsStraight(),
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},
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at(0, 0),
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);
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it('travels any distance in a straight line', () => {
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// §2.4 — "regardless of distance".
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const area = basicArea();
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const dests = reachableDestinations(ctxFor(area), at(0, 1), 'w');
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assert.ok(has(dests, 0, 0), 'reaches the office');
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assert.ok(has(dests, 0, -1), 'reaches past it');
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});
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it('branches onto Secondary Track through the Office stub', () => {
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const area = basicArea();
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const dests = reachableDestinations(ctxFor(area), at(0, 1), 'w');
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assert.ok(has(dests, 1, 0), 'reaches the card north of the office');
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});
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it('never reverses within a single Move', () => {
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// Leaving east from the west end cannot double back to the west end.
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const area = basicArea();
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const dests = reachableDestinations(ctxFor(area), at(0, -1), 'e');
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assert.ok(!has(dests, 0, -1), 'a Move may not return to its own start');
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});
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it('separates forward and reverse into different Moves', () => {
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const area = basicArea();
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const both = allReachable(ctxFor(area), at(0, 0), 'e');
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assert.ok(has(both.forward, 0, 1));
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assert.ok(has(both.reverse, 0, -1));
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assert.ok(!has(both.forward, 0, -1), 'reverse destinations must cost their own Move');
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});
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it('will not stop on a turnout', () => {
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// row 1: [C n-s straight]
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// row 0: [start] [turnout ]
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const area = areaFrom(
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{
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[coordKey(at(0, 0))]: straight(),
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[coordKey(at(0, 1))]: turnout({ stem: 'w', through: 'e', diverge: 'n' }),
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[coordKey(at(1, 1))]: nsStraight(),
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},
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at(0, 0),
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);
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const dests = reachableDestinations(ctxFor(area), at(0, 0), 'e');
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assert.ok(!has(dests, 0, 1), 'a turnout carries no wheel icon (§A.1)');
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assert.ok(has(dests, 1, 1), 'but a train may pass through it');
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});
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it('will not stop on a facility whose track is locked by a load', () => {
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// §9.3 — while any load sits on MEN|AT|WORK the industry track is not Operational Rail.
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const area = areaFrom(
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{
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[coordKey(at(0, 0))]: straight(),
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[coordKey(at(0, 1))]: lockedFacility(),
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},
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at(0, 0),
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);
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const dests = reachableDestinations(ctxFor(area), at(0, 0), 'e');
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assert.ok(!has(dests, 0, 1), 'locked industry track must not accept a train');
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});
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});
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// ---------------------------------------------------------------------------
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describe('coupling', () => {
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const withCars = (n: number): OfficeArea =>
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areaFrom(
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{
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[coordKey(at(0, 0))]: straight(),
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[coordKey(at(0, 1))]: straight(Array.from({ length: n }, car)),
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[coordKey(at(0, 2))]: straight(),
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},
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at(0, 0),
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);
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it('couples cars met along the way, mandatorily', () => {
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// §A.4 — "you MUST pick them up. You may not go around them."
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const dests = reachableDestinations(ctxFor(withCars(2)), at(0, 0), 'e');
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const beyond = dests.find((d) => d.coord.col === 2);
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assert.ok(beyond, 'should be able to pass the occupied card');
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assert.equal(beyond.couples.length, 2, 'cars must be collected, not stepped over');
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});
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it('forbids a Move that would overfill the tray', () => {
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// §A.4 — max four Rolling Stock, cabooses included. Overfilling makes the move illegal
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// rather than picking up fewer cars.
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const ctx = ctxFor(withCars(3), { consistSize: 3 });
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const dests = reachableDestinations(ctx, at(0, 0), 'e');
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assert.equal(dests.length, 0, '3 in tray + 3 standing exceeds 4');
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});
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it('permits a Move that exactly fills the tray', () => {
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const ctx = ctxFor(withCars(2), { consistSize: 2 });
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const dests = reachableDestinations(ctx, at(0, 0), 'e');
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assert.ok(dests.length > 0, '2 + 2 = 4 is legal');
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});
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});
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// ---------------------------------------------------------------------------
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describe('occupancy', () => {
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const twoTrainArea = (): OfficeArea =>
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areaFrom(
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{
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[coordKey(at(0, 0))]: straight(),
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[coordKey(at(0, 1))]: straight(),
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[coordKey(at(0, 2))]: straight(),
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},
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at(0, 5), // office elsewhere, so col 1 is ordinary track
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);
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it('blocks a card another train occupies', () => {
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// §A.4 — two trains may not share a card or move through each other.
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const occupancy: Occupancy = {
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trayAt: (c) => (c.row === 0 && c.col === 1 ? 'other' : null),
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freeAdTracks: () => 1,
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};
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const dests = reachableDestinations(ctxFor(twoTrainArea(), { occupancy }), at(0, 0), 'e');
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assert.ok(!has(dests, 0, 1), 'occupied card');
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assert.ok(!has(dests, 0, 2), 'and no passing through it');
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});
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it('allows passing through the Office while A/D tracks remain free', () => {
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const area = areaFrom(
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{
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[coordKey(at(0, 0))]: straight(),
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[coordKey(at(0, 1))]: officeCard(),
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[coordKey(at(0, 2))]: straight(),
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},
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at(0, 1),
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);
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const occupancy: Occupancy = {
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trayAt: (c) => (c.row === 0 && c.col === 1 ? 'other' : null),
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freeAdTracks: () => 1,
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};
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const dests = reachableDestinations(ctxFor(area, { occupancy }), at(0, 0), 'e');
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assert.ok(has(dests, 0, 2), 'the Office is the exception to the blocking rule (§A.4)');
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});
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it('blocks the Office once every A/D track is taken', () => {
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const area = areaFrom(
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{
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[coordKey(at(0, 0))]: straight(),
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[coordKey(at(0, 1))]: officeCard(),
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[coordKey(at(0, 2))]: straight(),
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},
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at(0, 1),
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);
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const occupancy: Occupancy = {
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trayAt: (c) => (c.row === 0 && c.col === 1 ? 'other' : null),
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freeAdTracks: () => 0,
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};
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const dests = reachableDestinations(ctxFor(area, { occupancy }), at(0, 0), 'e');
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assert.ok(!has(dests, 0, 2));
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});
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});
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// ---------------------------------------------------------------------------
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describe('placement and drop-off', () => {
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it('lets the first Facility attach to the Office stub', () => {
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// Gap 8 — the case that was impossible before Office cards carried junction stubs.
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const area = areaFrom(
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{
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[coordKey(at(0, -1))]: straight(),
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[coordKey(at(0, 0))]: officeCard(),
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[coordKey(at(0, 1))]: straight(),
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},
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at(0, 0),
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);
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assert.ok(canPlaceAt(area, at(1, 0), nsStraight()), 'north of the Office');
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assert.ok(canPlaceAt(area, at(-1, 0), nsStraight()), 'south of the Office');
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});
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it('refuses a card whose ports do not meet the neighbour it touches', () => {
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// Gap 11 in miniature: an east-west straight placed north of the Office has no south port,
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// so it cannot attach to the stub. Orientation is not cosmetic.
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const area = areaFrom(
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{
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[coordKey(at(0, -1))]: straight(),
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[coordKey(at(0, 0))]: officeCard(),
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[coordKey(at(0, 1))]: straight(),
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},
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at(0, 0),
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);
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assert.ok(!canPlaceAt(area, at(1, 0), straight()), 'e-w straight cannot meet a n-s stub');
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});
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it('refuses a card that connects to nothing', () => {
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const area = areaFrom({ [coordKey(at(0, 0))]: officeCard() }, at(0, 0));
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assert.ok(!canPlaceAt(area, at(3, 3), straight()), 'orphaned track is never legal');
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});
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it('refuses to place on an occupied cell', () => {
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const area = areaFrom({ [coordKey(at(0, 0))]: officeCard() }, at(0, 0));
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assert.ok(!canPlaceAt(area, at(0, 0), straight()));
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});
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it('forbids dropping cars at the Office', () => {
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// §A.4 — a passenger platform is no place to switch Rolling Stock.
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const area = areaFrom(
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{
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[coordKey(at(0, 0))]: officeCard(),
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[coordKey(at(0, 1))]: straight(),
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},
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at(0, 0),
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);
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assert.ok(!canDropCarsAt(area, at(0, 0)), 'Office track');
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assert.ok(canDropCarsAt(area, at(0, 1)), 'ordinary Operational Rail');
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});
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it('forbids dropping cars on a locked industry track', () => {
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const area = areaFrom(
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{
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[coordKey(at(0, 0))]: officeCard(),
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[coordKey(at(0, 1))]: lockedFacility(),
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},
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at(0, 0),
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);
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assert.ok(!canDropCarsAt(area, at(0, 1)));
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});
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});
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