refactored checksum validation to eliminate redundant operations

pyproject.toml

@@ -7,7 +7,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "veeder_root_tls_socket_library"
-version = "1.0.5"
+version = "1.1.0"
 authors = [ {name = "Evan Redden", email = "redden.evan@gmail.com"} ]
 description = "Socket library for querying and extracting data from Veeder-Root TLS systems."
 readme = "README.md"

src/veeder_root_tls_socket_library/socket.py

@@ -94,7 +94,7 @@ def execute(self,
 
         return self.__handle_response(byte_response, byte_command, is_display)
 
-    def __handle_response(self, byte_response: bytes, 
+    def _handle_response(self, byte_response: bytes, 
                           byte_command: bytes, is_display: bool) -> str:
         """
         Handles responses from the TLS system after executing a command.
@@ -133,7 +133,7 @@ def __handle_response(self, byte_response: bytes,
 
         return response
 
-    def __data_integrity_check(self, byte_response: bytes) -> bool:
+    def _data_integrity_check(self, byte_response: bytes) -> bool:
         """
         Verifies whether or not a command response retains its integrity
         after transmission by comparing it against the response checksum.
@@ -145,18 +145,11 @@ def __data_integrity_check(self, byte_response: bytes) -> bool:
         response = byte_response.decode()
         message  = response[:-5]
         checksum = response[-5:-1]
+        integrity_threshold = "0b10000000000000000"
 
         # Calculate the 16-bit binary count of the message.
-        message_int = sum(ord(char) for char in message) & 0xFFFF
-
-        # Convert message integer to twos complement integer.
-        message_int = message_int + (message_int >> 16)
-
-        # Convert checksum hexadecimal string into integer.
+        message_sum = sum(ord(char) for char in message)
         checksum_int = int(checksum, 16)
 
         # Compare sum of checksum and message to expected result.
-        integrity_threshold = "0b10000000000000000"
-        binary_sum = bin(message_int + checksum_int)
-
-        return binary_sum == integrity_threshold
+        return bin(message_sum + checksum_int) == integrity_threshold

tests/test_socket.py

@@ -35,5 +35,24 @@ def test_invalid_command(self):
             with self.assertRaises(ValueError):
                 tls.execute("test")
 
+    def test_checksum(self):
+        """
+        Verify that TlsSocket._data_integrity_check() correctly validates outputs.
+        """
+
+        # Cases are tuples with the full command output and expected checksum validation result.
+        cases = [
+            (b"\x01i101002312301342020402&&FB3B\x03", True),
+            (b"\x01i101002312301342020402&&FB3A\x03", False),
+            (b"\x01j101002312301342020402&&FB3B\x03", False)
+        ]
+
+        with TlsSocket(self.ip, self.port) as tls:
+            for case in cases:
+                actual = tls._data_integrity_check(case[0])
+                expected = case[1]
+
+                self.assertEqual(actual, expected)
+
 if __name__ == "__main__":
     unittest.main()