Add tests for recursive_unicode function

src/tribler/core/utilities/tests/test_unicode.py

@@ -0,0 +1,46 @@
+from tribler.core.utilities.unicode import recursive_unicode
+
+
+def test_recursive_unicode_empty():
+    # Test that recursive_unicode works on empty items
+    assert recursive_unicode({}) == {}
+    assert recursive_unicode([]) == []
+    assert recursive_unicode(b'') == ''
+    assert recursive_unicode('') == ''
+    assert recursive_unicode(None) is None
+
+
+def test_recursive_unicode_complex_object():
+    # Test that recursive_unicode works on a complex object
+    obj = {
+        'list': [
+            b'binary',
+            {}
+        ],
+        'sub dict': {
+            'sub list': [
+                1,
+                b'binary',
+                {
+                    '': b''
+                },
+            ]
+        }
+    }
+
+    expected = {
+        'list': [
+            'binary',
+            {}
+        ],
+        'sub dict': {
+            'sub list': [
+                1,
+                'binary',
+                {
+                    '': ''
+                },
+            ]
+        }
+    }
+    assert recursive_unicode(obj) == expected