map: click a region to switch the dossier to its owner; fix "no owner" (v0.7.0)

server/map.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest';
 import { buildRegionMap } from './map';
-import { nationColor } from '../shared/protocol';
+import { nationColor, regionOwner, type RegionMap } from '../shared/protocol';
 import type { GameState } from '../shared/types';
 
 const state: GameState = {
@@ -33,6 +33,9 @@ const state: GameState = {
   version: 1,
 };
 
+// The RegionMap built from the fixture: the authoritative ISO_A3 → owner source.
+const regions: RegionMap = buildRegionMap(state);
+
 describe('buildRegionMap', () => {
   it('maps each ISO_A3 region to its owner + that nation\'s stable color', () => {
     const m = buildRegionMap(state);
@@ -44,6 +47,67 @@ describe('buildRegionMap', () => {
   });
 });
 
+describe('regionOwner', () => {
+  it('resolves an owned region\'s ISO_A3 to its owner record', () => {
+    expect(regionOwner(regions, 'GBR')).toEqual({
+      color: nationColor('uk'),
+      owner: 'UK',
+      ownerId: 'uk',
+    });
+    expect(regionOwner(regions, 'DEU')).toEqual({
+      color: nationColor('de'),
+      owner: 'DE',
+      ownerId: 'de',
+    });
+  });
+
+  it('returns undefined for an unowned region (no RegionMap entry)', () => {
+    expect(regionOwner(regions, 'FRA')).toBeUndefined();
+    expect(regionOwner(regions, 'USA')).toBeUndefined();
+  });
+
+  it('returns undefined for an empty or missing code', () => {
+    expect(regionOwner(regions, '')).toBeUndefined();
+    expect(regionOwner(regions, null)).toBeUndefined();
+    expect(regionOwner(regions, undefined)).toBeUndefined();
+  });
+});
+
+/**
+ * #6 regression guard. The click/hover handlers resolve the owning nation from a
+ * map feature. MapLibre repacks a GeoJSON source's top-level `id` (the ISO_A3
+ * string) into a *numeric index* when it stores the source, so a feature the map
+ * hands back at interaction time has a number for `id` and the ISO_A3 only lives
+ * in `properties.regionId`. This test pins the exact data shape and proves the
+ * fix: resolution via `properties.regionId` works, while the pre-fix path that
+ * read `feature.id` does not.
+ */
+describe('#6 — owner must be resolved from properties.regionId, not the repacked feature.id', () => {
+  // The shape MapLibre returns for a source feature after setData(): `id` is a
+  // number (here 0, as observed in the live map), and the ISO_A3 is preserved
+  // only in properties (the client stamps it as `regionId`).
+  const repackedFeature = {
+    id: 0,
+    properties: { name: 'DE', regionId: 'DEU' },
+  };
+
+  it('resolves the owner from properties.regionId (the fix)', () => {
+    const code = typeof repackedFeature.properties.regionId === 'string' ? repackedFeature.properties.regionId : '';
+    expect(regionOwner(regions, code)).toEqual({
+      color: nationColor('de'),
+      owner: 'DE',
+      ownerId: 'de',
+    });
+  });
+
+  it('the old path (feature.id as a string key) does NOT resolve — the bug', () => {
+    // String(0) === '0' is not a valid ISO_A3 key, so the pre-fix lookup failed
+    // and the click popup reported "No owner" even for owned regions.
+    expect(regions[String(repackedFeature.id)]).toBeUndefined();
+    expect(regionOwner(regions, String(repackedFeature.id))).toBeUndefined();
+  });
+});
+
 describe('nationColor', () => {
   it('is deterministic per id and distinct across different ids', () => {
     expect(nationColor('uk')).toBe(nationColor('uk'));