NBL-64: Python: Allow signed byte values in ByteArray

This resolves #327

Author: isapego

pygridgain/datatypes/primitive_arrays.py

@@ -220,7 +220,22 @@ def from_python(cls, value):
         # no need to iterate on bytes or bytearray
         # to create ByteArrayObject data buffer
         header.length = len(value)
-        return bytes(bytearray(header) + bytearray(value))
+        try:
+            # `value` is a `bytearray` or a sequence of integer values
+            # in range 0 to 255
+            value_buffer = bytearray(value)
+        except ValueError:
+            # `value` is a sequence of integers in range -128 to 127
+            value_buffer = bytearray()
+            for ch in value:
+                if -128 <= ch <= 255:
+                    value_buffer.append(ctypes.c_ubyte(ch).value)
+                else:
+                    raise ValueError(
+                        'byte must be in range(-128, 256)!'
+                    ) from None
+
+        return bytes(bytearray(header) + value_buffer)
 
 
 class ShortArrayObject(PrimitiveArrayObject):

tests/test_datatypes.py

@@ -13,13 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+import ctypes
 from datetime import datetime, timedelta
 import decimal
 import pytest
 import uuid
 
 from pygridgain.api.key_value import cache_get, cache_put
 from pygridgain.datatypes import *
+from pygridgain.utils import unsigned
 
 
 @pytest.mark.parametrize(
@@ -143,6 +145,7 @@ def test_put_get_data(client, cache, value, value_hint):
     [
         [1, 2, 3, 5],
         (7, 8, 13, 18),
+        (-128, -1, 0, 1, 127, 255),
     ]
 )
 def test_bytearray_from_list_or_tuple(client, cache, value):
@@ -160,7 +163,9 @@ def test_bytearray_from_list_or_tuple(client, cache, value):
 
     result = cache_get(conn, cache, 'my_key')
     assert result.status == 0
-    assert result.value == bytearray(value)
+    assert result.value == bytearray([
+        unsigned(ch, ctypes.c_ubyte) for ch in value
+    ])
 
 
 @pytest.mark.parametrize(