add one more test

tests/abortable-falsy.spec.ts

+import { abortable } from '../src/abortable';
+
+describe('abortable() - falsy truthiness 行为', () => {
+  test('默认（不装箱）: 所有原始 falsy 仍为 falsy', () => {
+    const ac = new AbortController();
+    const s = ac.signal;
+
+    const cases: any[] = [false, 0, -0, 0n, '', null, undefined, NaN];
+
+    for (const v of cases) {
+      const wrapped = abortable(v, s); // 默认 boxPrimitives=false
+      expect(Boolean(wrapped)).toBe(false);
+    }
+  });
+
+  test('负例说明：开启 boxPrimitives=true 会把原始值装箱为对象（变成 truthy）', () => {
+    const ac = new AbortController();
+    const s = ac.signal;
+
+    const cases: any[] = [false, 0, -0, 0n, '', null, undefined, NaN];
+
+    for (const v of cases) {
+      const wrapped = abortable(v, s, { boxPrimitives: true });
+      // 被装箱后成为对象（或 {}），对象的 truthiness 恒为 true
+      expect(Boolean(wrapped)).toBe(true);
+    }
+
+    // 非原始值（对象/数组/函数）无论是否装箱，本来就是 truthy
+    const obj = {};
+    expect(Boolean(abortable(obj, s))).toBe(true);
+    expect(Boolean(abortable(obj, s, { boxPrimitives: true }))).toBe(true);
+  });
+});