New API: rename "update" function in a few classes

The method name "update" is ambigious and doesn't tell what we
are actually updating.
Are we updating one or all meta files in Snapshot?
Are we updating one or all target files in Targets?
Are we updating "version", "spec_version" or what in Timestamp?

Signed-off-by: Martin Vrachev <mvrachev@vmware.com>

Author: Martin Vrachev

tests/test_api.py

@@ -232,11 +232,11 @@ def test_metadata_snapshot(self):
 
 
         self.assertNotEqual(snapshot.signed.meta, fileinfo)
-        snapshot.signed.update('role1', 2, 123, hashes)
+        snapshot.signed.update_meta_file('role1', 2, 123, hashes)
         self.assertEqual(snapshot.signed.meta, fileinfo)
 
         # Update only version. Length and hashes are optional.
-        snapshot.signed.update('role1', 3)
+        snapshot.signed.update_meta_file('role1', 3)
         fileinfo['role1.json'] = MetaFile(3)
         self.assertEqual(snapshot.signed.meta, fileinfo)
 
@@ -271,11 +271,11 @@ def test_metadata_timestamp(self):
         fileinfo['snapshot.json'].version = 2
         fileinfo['snapshot.json'].length = 520
         self.assertNotEqual(timestamp.signed.meta, fileinfo)
-        timestamp.signed.update(2, 520, hashes)
+        timestamp.signed.update_snapshot_meta(2, 520, hashes)
         self.assertEqual(timestamp.signed.meta, fileinfo)
 
         # Update only version. Length and hashes are optional.
-        timestamp.signed.update(3)
+        timestamp.signed.update_snapshot_meta(3)
         fileinfo['snapshot.json'] = MetaFile(version=3)
         self.assertEqual(timestamp.signed.meta, fileinfo)
 
@@ -333,7 +333,7 @@ def test_metadata_targets(self):
         # Assert that data is not aleady equal
         self.assertNotEqual(targets.signed.targets[filename], fileinfo)
         # Update an already existing fileinfo
-        targets.signed.update(filename, fileinfo)
+        targets.signed.update_target(filename, fileinfo)
         expected_target_file = TargetFile(length=28, hashes=hashes)
         # Verify that data is updated
         self.assertEqual(targets.signed.targets[filename], expected_target_file)

tuf/api/metadata.py

@@ -506,7 +506,7 @@ def to_dict(self) -> JsonDict:
 
 
     # Modification.
-    def update(self, version: int, length: Optional[int] = None,
+    def update_snapshot_meta(self, version: int, length: Optional[int] = None,
             hashes: Optional[JsonDict] = None) -> None:
         """Assigns passed info about snapshot metadata to meta dict. """
 
@@ -557,7 +557,7 @@ def to_dict(self) -> JsonDict:
 
 
     # Modification.
-    def update(
+    def update_meta_file(
             self, rolename: str, version: int, length: Optional[int] = None,
             hashes: Optional[JsonDict] = None) -> None:
         """Assigns passed (delegated) targets role info to meta dict. """
@@ -705,7 +705,7 @@ def to_dict(self) -> JsonDict:
         return json_dict
 
     # Modification.
-    def update(self, filename: str, fileinfo: JsonDict) -> None:
+    def update_target(self, filename: str, fileinfo: JsonDict) -> None:
         """Assigns passed target file info to meta dict. """
         self.targets[filename] = TargetFile(fileinfo['length'],
             fileinfo['hashes'], fileinfo.get('custom'))