Fixed bug with 0-size bitmap (.grow(x))

Add testcase
Add tests script & config

jest.config.js

@@ -0,0 +1,7 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} **/
+export default {
+  testEnvironment: "node",
+  transform: {
+    "^.+\.tsx?$": ["ts-jest",{}],
+  },
+};

package.json

@@ -21,7 +21,8 @@
     "predeploy": "npm run dist",
     "lint": "eslint src --ext .ts",
     "lint:fix": "eslint src --ext .ts --fix",
-    "format": "prettier --write ./src/**/*.ts"
+    "format": "prettier --write ./src/**/*.ts",
+    "test": "jest"
   },
   "devDependencies": {
     "@jest/globals": "^29.7.0",
@@ -32,8 +33,10 @@
     "@typescript-eslint/parser": "^7.15.0",
     "eslint": "^9.6.0",
     "eslint-config-prettier": "^9.1.0",
+    "jest": "^29.7.0",
     "prettier": "^3.3.2",
     "rollup-plugin-typescript-paths": "^1.5.0",
+    "ts-jest": "^29.3.1",
     "tslib": "^2.6.3",
     "typescript": "^5.5.3",
     "vite": "^5.3.3",

src/bitmap.test.ts

@@ -2,13 +2,13 @@ import { Bitmap } from "./bitmap";
 
 describe("Bitmap", () => {
   test("Set", () => {
-    const x = 2;
-    const y = 4;
-    const bitmap = new Bitmap(32);
-    bitmap.set(x);
-    bitmap.set(y);
-    expect(bitmap.contains(x)).toBe(true);
-    expect(bitmap.contains(y)).toBe(true);
+    const bitmap = new Bitmap(0);
+    bitmap.set(0);
+    bitmap.set(1);
+    bitmap.set(2);
+    expect(bitmap.contains(0)).toBe(true);
+    expect(bitmap.contains(1)).toBe(true);
+    expect(bitmap.contains(2)).toBe(true);
   });
 
   test("Remove", () => {

src/bitmap.ts

@@ -12,12 +12,8 @@ export class Bitmap implements IBitmap {
     this.bits = new Uint8Array(computeBitsArrayLength(x));
   }
 
-  protected getBits(): Uint8Array {
-    return this.bits;
-  }
-
   public grow(x: number): void {
-    const arrLength = computeBitsArrayLength(x);
+    const arrLength = Math.max(1, computeBitsArrayLength(x));
     if (arrLength <= this.bits.length) return;
     const prev = this.bits;
     this.bits = new Uint8Array(arrLength);
@@ -55,6 +51,7 @@ export class Bitmap implements IBitmap {
     }
     return count;
   }
+
   public and(bitmap: IBitmap): IBitmap {
     const otherBits = (bitmap as Bitmap).bits;
     const result = this.clone() as Bitmap;
@@ -116,6 +113,7 @@ export class Bitmap implements IBitmap {
       if (!needContinueIterating) break;
     }
   }
+
   public filter(fn: (x: number) => boolean): void {
     for (let i = 0; i < this.bits.length; i++) {
       for (let j = 0; j < 8; j++) {
@@ -126,6 +124,7 @@ export class Bitmap implements IBitmap {
       }
     }
   }
+
   public clear(): void {
     for (let i = 0; i < this.bits.length; i++) {
       this.bits[i] = 0;