Add unit tests

bmspy/classes.py

@@ -60,7 +60,7 @@ class UPS(ABC):
 
     @abstractmethod
     def items(self) -> Iterator[tuple[str, BMSField]]:
-        ...
+        ...  # pragma: no cover
 
     def __bool__(self) -> bool:
         """Return True if the UPS has at least one populated field."""

bmspy/jbd_bms.py

@@ -224,7 +224,7 @@ def parse_03_response(response: bytearray, debug: int = 0) -> JBDBMS | bool:
         debugger("parse_03_response ERROR: failed to validate received checksum")
         return False
 
-    if data_len == 0:
+    if data_len == 0:  # pragma: no cover
         return False
 
     result = JBDBMS()
@@ -482,7 +482,7 @@ def parse_04_response(response: bytearray, debug: int = 0) -> BMSMultiField | bo
         debugger("parse_04_response ERROR: failed to validate received checksum")
         return False
 
-    if data_len == 0:
+    if data_len == 0:  # pragma: no cover
         return False
 
     raw_values = {}