Add some tests, minor change to the error messages

Author: Ezibenroc

pyroaring/abstract_bitmap.pxi

@@ -18,12 +18,12 @@ cdef croaring.roaring_bitmap_t *deserialize_ptr(bytes buff):
     buff_size = len(buff)
     ptr = croaring.roaring_bitmap_portable_deserialize_safe(buff, buff_size)
     if ptr == NULL:
-      raise ValueError("Could not deserialize bitmap!!")
+      raise ValueError("Could not deserialize bitmap")
     # Validate the bitmap
     if not croaring.roaring_bitmap_internal_validate(ptr, &reason_failure):
         # If validation fails, free the bitmap and raise an exception
         croaring.roaring_bitmap_free(ptr)
-        raise ValueError(f"Invalid bitmap: {reason_failure.decode('utf-8')}")
+        raise ValueError(f"Invalid bitmap after deserialization: {reason_failure.decode('utf-8')}")
     return ptr
 
 cdef croaring.roaring64_bitmap_t *deserialize64_ptr(bytes buff):

test.py

@@ -12,6 +12,7 @@
 import operator
 import unittest
 import functools
+import base64
 from typing import TYPE_CHECKING
 from collections.abc import Set, Callable, Iterable, Iterator
 
@@ -886,6 +887,27 @@ def test_pickle_protocol(
         assert old_bm == new_bm
         self.assert_is_not(old_bm, new_bm)
 
+    @given(bitmap_cls)
+    def test_impossible_deserialization(
+        self,
+        cls: type[EitherBitMap],
+    ) -> None:
+        wrong_input = base64.b64decode('aGVsbG8gd29ybGQ=')
+        with pytest.raises(ValueError, match='Could not deserialize bitmap'):
+            bitmap = cls.deserialize(wrong_input)
+
+    @given(bitmap_cls)
+    def test_invalid_deserialization(
+        self,
+        cls: type[EitherBitMap],
+    ) -> None:
+        wrong_input = base64.b64decode('aGVsbG8gd29ybGQ=')
+        bm = cls(list(range(0, 1000000, 3)))
+        bitmap_bytes = bm.serialize()
+        bitmap_bytes = bitmap_bytes[:42] + wrong_input + bitmap_bytes[42:]
+        with pytest.raises(ValueError, match='Invalid bitmap after deserialization'):
+            bitmap = pyroaring.FrozenBitMap.deserialize(bitmap_bytes)
+
 
 class TestStatistics(Util):