test: expand stripControlCharacters edge-case coverage (#554)

- Empty string and printable-only strings pass through unchanged.
- Boundary controls NUL (0x00), US (0x1F), and DEL (0x7F).
- Multiple control characters stripped in one string.

Addresses review feedback on regex /[\x00-\x1F\x7F]/g coverage from #553.

Author: rinchen

src/renderer/lib/stripControlCharacters.test.ts

@@ -3,8 +3,30 @@ import { describe, expect, it } from 'vitest';
 import { stripControlCharacters } from './stripControlCharacters';
 
 describe('stripControlCharacters', () => {
+  it('returns empty string unchanged', () => {
+    expect(stripControlCharacters('')).toBe('');
+  });
+
+  it('returns strings with no control characters unchanged', () => {
+    expect(stripControlCharacters('hello world')).toBe('hello world');
+    expect(stripControlCharacters('printable: ABC 123 !@#')).toBe('printable: ABC 123 !@#');
+  });
+
   it('removes ASCII control characters and keeps printable text', () => {
     expect(stripControlCharacters('hello\x07world')).toBe('helloworld');
     expect(stripControlCharacters('line\x1fbreak')).toBe('linebreak');
   });
+
+  it('removes boundary control characters (NUL and US)', () => {
+    expect(stripControlCharacters('\x00start')).toBe('start');
+    expect(stripControlCharacters('end\x1f')).toBe('end');
+  });
+
+  it('removes DEL (0x7F)', () => {
+    expect(stripControlCharacters('del\x7fchar')).toBe('delchar');
+  });
+
+  it('removes multiple control characters in one string', () => {
+    expect(stripControlCharacters('\x00a\x1fb\x7fc')).toBe('abc');
+  });
 });