diff --git a/src/logger/console-logger.service.spec.ts b/src/logger/console-logger.service.spec.ts
new file mode 100644
index 000000000..ae47a99ea
--- /dev/null
+++ b/src/logger/console-logger.service.spec.ts
@@ -0,0 +1,38 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { ConsoleLoggerService } from './console-logger.service';
+
+describe('sanitize', () => {
+  it('removes non-printable ASCII character', () => {
+    for (let i = 0; i++; i < 32) {
+      const hexString = i.toString(16);
+      expect(ConsoleLoggerService.sanitize(`a${hexString}b`)).toEqual('ab');
+    }
+  });
+  it('replaces non-zero-width space with space', () => {
+    const nonZeroWidthSpaces = [
+      '\u0020', // space
+      '\u00A0', // non-breaking space
+      '\u2000', // en quad
+      '\u2001', // en quad
+      '\u2002', // en space
+      '\u2003', // en space
+      '\u2004', // three-per-em space
+      '\u2005', // four-per-em space
+      '\u2006', // six-per-em space
+      '\u2007', // figure space
+      '\u2008', // punctuation space
+      '\u2009', // thin space
+      '\u200a', // hair space
+      '\u202F', // narrow no-break space
+      '\u205F', // medium mathematical space
+      '\u3000', // ideographic space
+    ];
+    nonZeroWidthSpaces.forEach((space) => {
+      expect(ConsoleLoggerService.sanitize(`c${space}d`)).toEqual('c d');
+    });
+  });
+});