Add the content_length field to the Document base class

earthsnake/document/__init__.py

@@ -19,6 +19,11 @@ class Document(ABC):  # pragma: no cover pylint: disable=too-few-public-methods
 
     signature: Optional[str]
 
+    @property
+    @abstractmethod
+    def content_length(self) -> int:
+        """The length of the document"""
+
     @abstractmethod
     def sign(self, identity: Optional[Identity] = None) -> None:
         """Sign the document as identity

earthsnake/document/es4.py

@@ -221,6 +221,10 @@ class Es4Document(Document):  # pylint: disable=too-many-instance-attributes
         self._content = value
         self._content_hash = self.hash_value(value)
 
+    @property
+    def content_length(self) -> int:
+        return len(self._content)
+
     def generate_hash(self) -> str:
         """Calculate the hash of the document
 

tests/test_document_es4.py

@@ -272,3 +272,11 @@ def test_validate_unsigned_document(identity: Identity) -> None:
         document.validate_signature()
 
     assert str(ctx.value) == 'document has no signature assigned'
+
+
+def test_content_length() -> None:
+    """Test the content_length property"""
+
+    document = Es4Document.from_json(VALID_DOCUMENT)
+
+    assert document.content_length == 4