Fixed some review comments and extended tests to cover more use cases

Author: DavyGillebert

canopen/sdo/constants.py

@@ -4,7 +4,7 @@
 
 # Command, index, subindex
 SDO_STRUCT = struct.Struct("<BHB")
-SDO_BLOCKINIT_STRUCT = "<BHBI"  # Command + seqno, index, subindex, size
+SDO_BLOCKINIT_STRUCT = struct.Struct("<BHBI")  # Command + seqno, index, subindex, size
 SDO_BLOCKACK_STRUCT = struct.Struct("<BBB") # c + ackseq + new blocksize
 SDO_BLOCKEND_STRUCT = struct.Struct("<BH") # c + CRC
 SDO_ABORT_STRUCT = struct.Struct("<BHBI") # c +i + si + Abort code

canopen/sdo/exceptions.py

@@ -60,15 +60,21 @@ def __str__(self):
             text = text + ", " + self.CODES[self.code]
         return text
 
-    def __eq__(self, other):
+    def __eq__(self, other:Union['SdoAbortedError', int, str]):
         """Compare two exception objects based on SDO abort code."""
+        if isinstance(other, int):
+            other = SdoAbortedError(other)
+        elif isinstance(other, str):
+            other = SdoAbortedError(other)
+        elif not isinstance(other, SdoAbortedError):
+            raise TypeError(f"Cannot compare SdoAbortedError with {type(other)}")
         return self.code == other.code
 
-    def from_string(self, text):
+    def from_string(self, text: str) -> int:
         code = list(SdoAbortedError.CODES.keys())[
             list(SdoAbortedError.CODES.values()).index(text)
         ]
-        return code
+        return SdoAbortedError(code)
 
 
 class SdoCommunicationError(SdoError):