Change "update()" argument types

Currently, when we call Targets/Snapshot/Timestamp.update() we are
passing all of the necessary values to create MetaFile/Targets File
respectively.
This is not needed, given that one of the reasons we have created
MetaFile and TargetFile is to make the API easier to use.

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

Author: MVrachev

tests/test_api.py

@@ -301,14 +301,14 @@ def test_metadata_snapshot(self):
         self.assertNotEqual(
             snapshot.signed.meta['role1.json'].to_dict(), fileinfo.to_dict()
         )
-        snapshot.signed.update('role1', 2, 123, hashes)
+        snapshot.signed.update('role1', fileinfo)
         self.assertEqual(
             snapshot.signed.meta['role1.json'].to_dict(), fileinfo.to_dict()
         )
 
         # Update only version. Length and hashes are optional.
-        snapshot.signed.update('role2', 3)
         fileinfo = MetaFile(3)
+        snapshot.signed.update('role2', fileinfo)
         self.assertEqual(
             snapshot.signed.meta['role2.json'].to_dict(), fileinfo.to_dict()
         )
@@ -353,7 +353,7 @@ def test_metadata_timestamp(self):
         self.assertNotEqual(
             timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
         )
-        timestamp.signed.update(2, 520, hashes)
+        timestamp.signed.update(fileinfo)
         self.assertEqual(
             timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
         )
@@ -367,8 +367,8 @@ def test_metadata_timestamp(self):
         self.assertEqual(timestamp_dict['signed'], timestamp_test.to_dict())
 
         # Update only version. Length and hashes are optional.
-        timestamp.signed.update(3)
         fileinfo = MetaFile(version=3)
+        timestamp.signed.update(fileinfo)
         self.assertEqual(
             timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
         )
@@ -593,7 +593,7 @@ def test_metadata_targets(self):
             targets.signed.targets[filename].to_dict(), fileinfo.to_dict()
         )
         # Update an already existing fileinfo
-        targets.signed.update(filename, fileinfo.to_dict())
+        targets.signed.update(filename, fileinfo)
         # Verify that data is updated
         self.assertEqual(
             targets.signed.targets[filename].to_dict(), fileinfo.to_dict()

tuf/api/metadata.py

@@ -700,14 +700,9 @@ def to_dict(self) -> Dict[str, Any]:
         return res_dict
 
     # Modification.
-    def update(
-        self,
-        version: int,
-        length: Optional[int] = None,
-        hashes: Optional[Dict[str, Any]] = None,
-    ) -> None:
+    def update(self, snapshot_meta: MetaFile) -> None:
         """Assigns passed info about snapshot metadata to meta dict."""
-        self.meta["snapshot.json"] = MetaFile(version, length, hashes)
+        self.meta["snapshot.json"] = snapshot_meta
 
 
 class Snapshot(Signed):
@@ -759,16 +754,10 @@ def to_dict(self) -> Dict[str, Any]:
         return snapshot_dict
 
     # Modification.
-    def update(
-        self,
-        rolename: str,
-        version: int,
-        length: Optional[int] = None,
-        hashes: Optional[Dict[str, Any]] = None,
-    ) -> None:
+    def update(self, rolename: str, role_info: MetaFile) -> None:
         """Assigns passed (delegated) targets role info to meta dict."""
         metadata_fn = f"{rolename}.json"
-        self.meta[metadata_fn] = MetaFile(version, length, hashes)
+        self.meta[metadata_fn] = role_info
 
 
 class DelegatedRole(Role):
@@ -1010,6 +999,6 @@ def to_dict(self) -> Dict[str, Any]:
         return targets_dict
 
     # Modification.
-    def update(self, filename: str, fileinfo: Dict[str, Any]) -> None:
+    def update(self, filename: str, fileinfo: TargetFile) -> None:
         """Assigns passed target file info to meta dict."""
-        self.targets[filename] = TargetFile.from_dict(fileinfo)
+        self.targets[filename] = fileinfo