Fixing unit tests

pyads/connection.py

@@ -50,6 +50,7 @@
     ads_type_to_ctype,
     PLCSimpleDataType,
     PLCDataType,
+    STRING_BUFFER,
 )
 from .filetimes import filetime_to_dt
 from .pyads_ex import (
@@ -445,7 +446,7 @@ def get_all_symbols(self) -> List[AdsSymbol]:
             symbol_size_msg = self.read(
                 ADSIGRP_SYM_UPLOADINFO2,
                 ADSIOFFS_DEVDATA_ADSSTATE,
-                PLCTYPE_STRING,
+                PLCTYPE_STRING * STRING_BUFFER,
                 return_ctypes=True,
             )
             sym_count = struct.unpack("I", symbol_size_msg[0:4])[0]

pyads/pyads_ex.py

@@ -269,7 +269,8 @@ def get_value_from_ctype_data(read_data: Optional[Any], plc_type: Type) -> Any:
         return read_data.value.decode("utf-8")
 
     if type_is_wstring(plc_type):
-        return read_data.value  # ctypes automatically decoded the string for us
+        # `read_data.value` also exists, but could be wrong - explicitly decode instead:
+        return bytes(read_data).decode("utf-16-le").rstrip("\x00")
 
     if type(plc_type).__name__ == "PyCArrayType":
         return list(read_data)
@@ -857,9 +858,13 @@ def adsSyncReadReqEx2(
     if error_code:
         raise ADSError(error_code)
 
-    # If we're reading a value of predetermined size (anything but wstring, regular
-    # strings also contain size), validate that the correct number of bytes were read
-    if check_length and bytes_read.value != data_length.value:
+    # If we're reading a value of predetermined size (anything but strings, which can be shorted
+    # because of null-termination), validate that the correct number of bytes were read
+    if (
+        check_length 
+        and not (type_is_string(data_type) or type_is_wstring(data_type))
+        and bytes_read.value != data_length.value
+    ):
         raise RuntimeError(
             "Insufficient data (expected {0} bytes, {1} were read).".format(
                 data_length.value, bytes_read.value

tests/test_connection_class.py

@@ -231,11 +231,9 @@ def test_read_string(self):
         # Assert that the server received the correct command
         self.assert_command_id(requests[0], constants.ADSCOMMAND_READ)
 
-        # The string buffer is 1024 bytes long, this will be filled with \x0F
-        # and null terminated with \x00 by our test server. The \x00 will get
-        # chopped off during parsing to python string type
-        expected_result = "\x0F" * 1023
-        self.assertEqual(result, expected_result)
+        # We are reading only a single character, which the test-server defaults at 0
+        expected_result = "\x00"
+        self.assertEqual(expected_result, result)
 
     def test_write_uint(self):
         value = 100
@@ -1451,7 +1449,7 @@ def test_read_wstring(self):
         var = PLCVariable(
             "wstr",
             expected1.encode("utf-16-le") + b"\x00\x00",
-            constants.ADST_WSTRING, "WSTRING"
+            constants.ADST_WSTRING, "WSTRING(80)"
         )
         self.handler.add_variable(var)