test(uniqBy): add property-key cases for uniqBy

Author: Yeom-JinHo

src/array/uniqBy.spec.ts

@@ -2,12 +2,12 @@ import { describe, expect, it } from 'vitest';
 import { uniqBy } from './uniqBy';
 
 describe('uniqBy', () => {
-  it('should work with a `mapper`', () => {
+  it('should work with a selector function (mapper)', () => {
     expect(uniqBy([2.1, 1.2, 2.3], Math.floor)).toEqual([2.1, 1.2]);
     expect(uniqBy([1.2, 1.5, 2.1, 3.2, 5.7, 5.3, 7.19], Math.floor)).toEqual([1.2, 2.1, 3.2, 5.7, 7.19]);
   });
 
-  it('should keep the first occurrence when duplicates are found', () => {
+  it('should keep the first occurrence when duplicates are found (selector function)', () => {
     const items = [
       { id: 1, value: 'apple' },
       { id: 2, value: 'banana' },
@@ -24,4 +24,42 @@ describe('uniqBy', () => {
       { id: 3, value: 'cherry' },
     ]);
   });
+  it('should work with a property key selector', () => {
+    const items = [
+      { id: 1, value: 'jinho' },
+      { id: 2, value: 'dohee' },
+      { id: 1, value: 'jihun' },
+      { id: 3, value: 'taeho' },
+      { id: 2, value: 'eunji' },
+    ];
+
+    const result = uniqBy(items, 'id');
+
+    expect(result).toEqual([
+      { id: 1, value: 'jinho' },
+      { id: 2, value: 'dohee' },
+      { id: 3, value: 'taeho' },
+    ]);
+  });
+
+  it('should work with a property key selector for string fields', () => {
+    const items = [
+      { category: 'fruit', name: 'apple' },
+      { category: 'fruit', name: 'banana' },
+      { category: 'vegetable', name: 'carrot' },
+      { category: 'vegetable', name: 'onion' },
+    ];
+
+    const result = uniqBy(items, 'category');
+
+    expect(result).toEqual([
+      { category: 'fruit', name: 'apple' },
+      { category: 'vegetable', name: 'carrot' },
+    ]);
+  });
+
+  it('should return an empty array when input is empty', () => {
+    expect(uniqBy([], Math.floor)).toEqual([]);
+    expect(uniqBy([] as Array<{ id: number }>, 'id')).toEqual([]);
+  });
 });