diff --git a/reimplement/set.py b/reimplement/set.py
index beb9c60..5ac4c5f 100644
--- a/reimplement/set.py
+++ b/reimplement/set.py
@@ -174,7 +174,6 @@ def decode_golomb(bits: List[int], Mshift: int) -> List[int]:
             if i < len(bits):
                 if bits[i] == 1:
                     r |= 1 << j
-            else:
                 i += 1
 
         delta_value = (q << Mshift) | r
@@ -360,28 +359,3 @@ def set_fini(set: Set, bpp: int) -> str | None:
     encoded_string = encode_set(hash_values, bpp)
 
     return encoded_string
-
-
-if __name__ == "__main__":
-    # Example usage
-    my_set = set_new()
-    set_add(my_set, "example_label_1")
-    set_add(my_set, "example_label_2")
-    result = set_fini(my_set, 8)
-    print(result)
-    set_free(my_set)
-
-    # example with comparison
-    set1 = set_new()
-    set_add(set1, "label1")
-    set_add(set1, "label2")
-    str1 = set_fini(set1, 8)
-    set2 = set_new()
-    set_add(set2, "label1")
-    set_add(set2, "label2")
-    set_add(set2, "label3")
-    str2 = set_fini(set2, 8)
-    assert str1 is not None and str2 is not None, "Set strings should not be None"
-    comparison_result = rpmsetcmp(str1, str2)
-    assert comparison_result == -1, "Expected str1 to be less than str2"
-    print(comparison_result)
diff --git a/tests/test_reimplement_set.py b/tests/test_reimplement_set.py
index 43678fc..917a241 100644
--- a/tests/test_reimplement_set.py
+++ b/tests/test_reimplement_set.py
@@ -1,20 +1,92 @@
+import contextlib
+import io
+import runpy
 import unittest
 
-from reimplement.set import downsample_set
+from reimplement import set as rpmset
+
+
+class Base64AlphabetTest(unittest.TestCase):
+    def test_int_to_char_and_char_to_int_roundtrip_all_values(self):
+        for value in range(64):
+            self.assertEqual(rpmset.char_to_int(rpmset.int_to_char(value)), value)
+
+    def test_int_to_char_rejects_out_of_range_values(self):
+        with self.assertRaises(ValueError):
+            rpmset.int_to_char(64)
+
+    def test_char_to_int_rejects_non_base64_character(self):
+        with self.assertRaises(ValueError):
+            rpmset.char_to_int("=")
+
+
+class GolombEncodingTest(unittest.TestCase):
+    def test_delta_roundtrip(self):
+        values = [1, 3, 6, 10, 31]
+        self.assertEqual(rpmset.decode_delta(rpmset.encode_delta(values)), values)
+
+    def test_golomb_roundtrip(self):
+        values = [0, 1, 2, 7, 8, 15]
+        bits = rpmset.encode_golomb(values, Mshift=3)
+        self.assertEqual(rpmset.decode_golomb(bits, Mshift=3), values)
+
+    def test_base64_roundtrip_preserves_bits_with_zero_padding(self):
+        bits = [1, 0, 1, 1, 0, 0, 1]
+        encoded = rpmset.encode_base64(bits)
+        self.assertEqual(rpmset.decode_base64(encoded)[: len(bits)], bits)
+
+
+class SetStringTest(unittest.TestCase):
+    def test_encode_decode_set_roundtrip(self):
+        values = [1, 3, 6, 10]
+        encoded = rpmset.encode_set(values, bpp=8)
+        bpp, mshift = rpmset.decode_set_init(encoded)
+        self.assertEqual(bpp, 8)
+        self.assertEqual(rpmset.decode_set(encoded, mshift)[: len(values)], values)
+
+    def test_set_add_fini_and_free(self):
+        item_set = rpmset.set_new()
+        rpmset.set_add(item_set, "label1")
+        rpmset.set_add(item_set, "label2")
+
+        encoded = rpmset.set_fini(item_set, bpp=8)
+        self.assertIsNotNone(encoded)
+        self.assertEqual(item_set.cnt, 2)
+        self.assertEqual(item_set.labels, sorted(item_set.labels, key=lambda item: item[1]))
+
+        rpmset.set_free(item_set)
+        self.assertEqual(item_set.cnt, 0)
+        self.assertEqual(item_set.labels, [])
+
+    def test_hash_is_stable_64_bit_ascii_integer(self):
+        self.assertEqual(rpmset.hash("ascii_symbol"), 10827468943333989194)
+        self.assertLessEqual(rpmset.hash("ascii_symbol"), 2**64 - 1)
+
+    def test_hash_rejects_non_ascii_labels(self):
+        with self.assertRaises(UnicodeEncodeError):
+            rpmset.hash("юникод")
 
 
 class DownsampleSetTest(unittest.TestCase):
     def test_masks_high_half_and_keeps_sorted_unique_values(self):
-        self.assertEqual(downsample_set([1, 3, 6, 8, 10, 14], 3), [0, 1, 2, 3, 6])
+        self.assertEqual(rpmset.downsample_set([1, 3, 6, 8, 10, 14], 3), [0, 1, 2, 3, 6])
 
     def test_removes_duplicates_created_by_masking(self):
-        self.assertEqual(downsample_set([1, 6, 14], 3), [1, 6])
+        self.assertEqual(rpmset.downsample_set([1, 6, 14], 3), [1, 6])
 
     def test_keeps_low_only_set_unchanged(self):
-        self.assertEqual(downsample_set([1, 3, 6], 3), [1, 3, 6])
+        self.assertEqual(rpmset.downsample_set([1, 3, 6], 3), [1, 3, 6])
 
     def test_masks_high_only_set(self):
-        self.assertEqual(downsample_set([8, 10, 14], 3), [0, 2, 6])
+        self.assertEqual(rpmset.downsample_set([8, 10, 14], 3), [0, 2, 6])
+
+
+class ModuleEntrypointTest(unittest.TestCase):
+    def test_module_has_no_main_side_effects(self):
+        output = io.StringIO()
+        with contextlib.redirect_stdout(output):
+            runpy.run_path("reimplement/set.py", run_name="__main__")
+        self.assertEqual(output.getvalue(), "")
 
 
 if __name__ == "__main__":