fixed DB class not allowing to write BYTE values to rows (#377)

previously, the DB_Row.set_value() method did not support setting BYTE
values. this commit introduces this functionality, as well as unit
tests.

Author: vmsh0

snap7/util.py

@@ -1613,6 +1613,7 @@ def set_value(self, byte_index: Union[str, int], type_: str, value: Union[bool,
                 'UINT': set_uint,
                 'INT': set_int,
                 'WORD': set_word,
+                'BYTE': set_byte,
                 'USINT': set_usint,
                 'SINT': set_sint,
             }

test/test_util.py

@@ -113,19 +113,31 @@
 
 class TestS7util(unittest.TestCase):
 
-    def test_get_byte(self):
+    def test_get_byte_new(self):
         test_array = bytearray(_new_bytearray)
         byte_ = util.get_byte(test_array, 41)
         self.assertEqual(byte_, 128)
         byte_ = util.get_byte(test_array, 42)
         self.assertEqual(byte_, 255)
 
-    def test_set_byte(self):
+    def test_set_byte_new(self):
         test_array = bytearray(_new_bytearray)
         util.set_byte(test_array, 41, 127)
         byte_ = util.get_byte(test_array, 41)
         self.assertEqual(byte_, 127)
 
+    def test_get_byte(self):
+        test_array = bytearray(_bytearray)
+        row = util.DB_Row(test_array, test_spec, layout_offset=4)
+        value = row.get_value(50, 'BYTE')  # get value
+        self.assertEqual(value, 254)
+
+    def test_set_byte(self):
+        test_array = bytearray(_bytearray)
+        row = util.DB_Row(test_array, test_spec, layout_offset=4)
+        row['testByte'] = 255
+        self.assertEqual(row['testByte'], 255)
+
     def test_get_s5time(self):
         """
         S5TIME extraction from bytearray