refactor: refacotr preference

packages/@vben-core/shared/toolkit/src/letter.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest';
+
+import { capitalizeFirstLetter, toLowerCaseFirstLetter } from './letter';
+
+// 编写测试用例
+describe('capitalizeFirstLetter', () => {
+  it('should capitalize the first letter of a string', () => {
+    expect(capitalizeFirstLetter('hello')).toBe('Hello');
+    expect(capitalizeFirstLetter('world')).toBe('World');
+  });
+
+  it('should handle empty strings', () => {
+    expect(capitalizeFirstLetter('')).toBe('');
+  });
+
+  it('should handle single character strings', () => {
+    expect(capitalizeFirstLetter('a')).toBe('A');
+    expect(capitalizeFirstLetter('b')).toBe('B');
+  });
+
+  it('should not change the case of other characters', () => {
+    expect(capitalizeFirstLetter('hElLo')).toBe('HElLo');
+  });
+});
+
+describe('toLowerCaseFirstLetter', () => {
+  it('should convert the first letter to lowercase', () => {
+    expect(toLowerCaseFirstLetter('CommonAppName')).toBe('commonAppName');
+    expect(toLowerCaseFirstLetter('AnotherKeyExample')).toBe(
+      'anotherKeyExample',
+    );
+  });
+
+  it('should return the same string if the first letter is already lowercase', () => {
+    expect(toLowerCaseFirstLetter('alreadyLowerCase')).toBe('alreadyLowerCase');
+  });
+
+  it('should handle empty strings', () => {
+    expect(toLowerCaseFirstLetter('')).toBe('');
+  });
+
+  it('should handle single character strings', () => {
+    expect(toLowerCaseFirstLetter('A')).toBe('a');
+    expect(toLowerCaseFirstLetter('a')).toBe('a');
+  });
+
+  it('should handle strings with only one uppercase letter', () => {
+    expect(toLowerCaseFirstLetter('A')).toBe('a');
+  });
+
+  it('should handle strings with special characters', () => {
+    expect(toLowerCaseFirstLetter('!Special')).toBe('!Special');
+    expect(toLowerCaseFirstLetter('123Number')).toBe('123Number');
+  });
+});