feat(coords): Chunk-Namen als Planquadrat A1 bis L12

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

tests/coords.test.js

@@ -1,5 +1,8 @@
 import { describe, expect, it } from "vitest";
-import { CHUNK_SIZE, chunkForWorld, threeToWorld, tileForWorld, worldToThree } from "../src/world/coords.js";
+import fs from "node:fs";
+import { CHUNK_SIZE, chunkForWorld, chunkName, parseChunkName, threeToWorld, tileForWorld, worldToThree } from "../src/world/coords.js";
+
+const NAMES = JSON.parse(fs.readFileSync(new URL("./fixtures/chunk-names.json", import.meta.url), "utf8"));
 
 describe("coords", () => {
     it("dreht Y zur three-z-Achse", () => {
@@ -22,3 +25,39 @@ describe("coords", () => {
         expect(chunkForWorld(1999, -499)).toEqual({ i: 11, j: 11 });
     });
 });
+
+describe("Chunk-Namen", () => {
+    it("benennt Ecken und Beispiel wie in der Spec, in beide Richtungen", () => {
+        for (const [name, i, j] of NAMES.pairs) {
+            expect(chunkName(i, j)).toBe(name);
+            expect(parseChunkName(name)).toEqual({ i, j });
+        }
+    });
+
+    it("akzeptiert Kleinschreibung", () => {
+        for (const [name, i, j] of NAMES.lowercase) expect(parseChunkName(name)).toEqual({ i, j });
+    });
+
+    it("weist alles außerhalb von A1 bis L12 ab", () => {
+        for (const name of NAMES.invalid) expect(parseChunkName(name)).toBeNull();
+    });
+
+    it("liefert null für Indizes außerhalb des Ausschnitts", () => {
+        expect(chunkName(12, 0)).toBeNull();
+        expect(chunkName(0, 12)).toBeNull();
+        expect(chunkName(-1, 3)).toBeNull();
+        expect(chunkName(1.5, 3)).toBeNull();
+    });
+
+    it("kommt für alle 144 Chunks hin und zurück", () => {
+        for (let i = 0; i < 12; i++) {
+            for (let j = 0; j < 12; j++) expect(parseChunkName(chunkName(i, j))).toEqual({ i, j });
+        }
+    });
+
+    it("verbindet den Namen mit der Lage: der Downtown-Kern liegt in B9", () => {
+        const { i, j } = chunkForWorld(-511, 254);
+        expect({ i, j }).toEqual({ i: 1, j: 8 });
+        expect(chunkName(i, j)).toBe("B9");
+    });
+});

tests/fixtures/chunk-names.json

@@ -0,0 +1,5 @@
+{
+  "pairs": [["A1", 0, 0], ["L1", 11, 0], ["A12", 0, 11], ["L12", 11, 11], ["C10", 2, 9]],
+  "lowercase": [["c10", 2, 9], ["l12", 11, 11]],
+  "invalid": ["M1", "A0", "A13", "A", "10", "", "A01", "B-3", " "]
+}