Move _calculate_delegation inside HashDelegations

Signed-off-by: Martin Vrachev <[email protected]>

tests/test_api.py

@@ -796,9 +796,12 @@ def test_find_delegation_with_succinct_hash_info(
             expected_rolename = test_data.result
             msg = f"Error for {hash_bits} expected {expected_rolename}"
 
-            # pylint: disable=protected-access
+            assert r.succinct_hash_info is not None
             self.assertEqual(
-                r._calculate_delegation(hash_bits), expected_rolename, msg
+                # pylint: disable=protected-access
+                r.succinct_hash_info._calculate_delegation(hash_bits),
+                expected_rolename,
+                msg,
             )
 
 

tuf/api/metadata.py

@@ -1319,6 +1319,21 @@ def to_dict(self) -> Dict[str, Any]:
             **self.unrecognized_fields,
         }
 
+    def _calculate_delegation(self, hash_bits_representation: str) -> str:
+        """Helper function for find_delegation calculating the actual rolename.
+
+        Args:
+            hash_bits_representation: binary bit representation of the target
+                hash.
+        """
+
+        bit_length = self.hash_prefix_len
+        # Get the first bit_length of bits and then cast them to decimal.
+        bin_number = int(hash_bits_representation[:bit_length], 2)
+
+        name_prefix = self.bin_name_prefix
+        return f"{name_prefix}-{bin_number}"
+
 
 class DelegatedRole(Role):
     """A container with information about a delegated role.
@@ -1475,25 +1490,6 @@ def _is_target_in_pathpattern(targetpath: str, pathpattern: str) -> bool:
 
         return True
 
-    def _calculate_delegation(self, hash_bits_representation: str) -> str:
-        """Helper function for find_delegation calculating the actual rolename.
-
-        Args:
-            hash_bits_representation: binary bit representation of the target
-                hash.
-        """
-        if self.succinct_hash_info is None:
-            raise ValueError(
-                "succinct_hash_info must be set to calculate the delegation"
-            )
-
-        bit_length = self.succinct_hash_info.hash_prefix_len
-        # Get the first bit_length of bits and then cast them to decimal.
-        bin_number = int(hash_bits_representation[:bit_length], 2)
-
-        name_prefix = self.succinct_hash_info.bin_name_prefix
-        return f"{name_prefix}-{bin_number}"
-
     def find_delegation(self, target_filepath: str) -> Optional[str]:
         """Find the delegated rolename based on the given ``target filepath``.
 
@@ -1518,7 +1514,8 @@ def find_delegation(self, target_filepath: str) -> Optional[str]:
                 f"{one_byte:08b}" for one_byte in hasher.digest()
             )
 
-            return self._calculate_delegation(hash_bits)
+            # pylint: disable=protected-access
+            return self.succinct_hash_info._calculate_delegation(hash_bits)
 
         return None