Drop python3.6 and remove the usage of OrderedDict

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
       # Run regular TUF tests on each OS/Python combination, plus special tests
       # (sslib master) and linters on Linux/Python3.x only.
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
         os: [ubuntu-latest, macos-latest, windows-latest]
         toxenv: [py]
         include:

examples/repo_example/basic_repo.py

@@ -25,7 +25,6 @@
 """
 import os
 import tempfile
-from collections import OrderedDict
 from datetime import datetime, timedelta
 from pathlib import Path
 from typing import Any, Dict
@@ -103,7 +102,7 @@ def _in(days: float) -> datetime:
     signed=Targets(
         version=1, spec_version=SPEC_VERSION, expires=_in(7), targets={}
     ),
-    signatures=OrderedDict(),
+    signatures={},
 )
 
 # For the purpose of this example we use the top-level targets role to protect
@@ -134,7 +133,7 @@ def _in(days: float) -> datetime:
         expires=_in(7),
         meta={"targets.json": MetaFile(version=1)},
     ),
-    OrderedDict(),
+    {},
 )
 
 # Timestamp (freshness)
@@ -156,7 +155,7 @@ def _in(days: float) -> datetime:
         expires=_in(1),
         snapshot_meta=MetaFile(version=1),
     ),
-    OrderedDict(),
+    {},
 )
 
 # Root (root of trust)
@@ -195,7 +194,7 @@ def _in(days: float) -> datetime:
         },
         consistent_snapshot=True,
     ),
-    signatures=OrderedDict(),
+    signatures={},
 )
 
 # NOTE: We only need the public part to populate root, so it is possible to use
@@ -292,7 +291,7 @@ def _in(days: float) -> datetime:
         expires=_in(7),
         targets={target_path: target_file_info},
     ),
-    signatures=OrderedDict(),
+    signatures={},
 )
 
 
@@ -313,20 +312,15 @@ def _in(days: float) -> datetime:
             keys[delegatee_name]
         )
     },
-    roles=OrderedDict(
-        [
-            (
-                delegatee_name,
-                DelegatedRole(
-                    name=delegatee_name,
-                    keyids=[keys[delegatee_name]["keyid"]],
-                    threshold=1,
-                    terminating=True,
-                    paths=["*.py"],
-                ),
-            )
-        ]
-    ),
+    roles={
+        delegatee_name: DelegatedRole(
+            name=delegatee_name,
+            keyids=[keys[delegatee_name]["keyid"]],
+            threshold=1,
+            terminating=True,
+            paths=["*.py"],
+        ),
+    },
 )
 
 # Remove target file info from top-level targets (delegatee is now responsible)

examples/repo_example/hashed_bin_delegation.py

@@ -19,7 +19,6 @@
 import hashlib
 import os
 import tempfile
-from collections import OrderedDict
 from datetime import datetime, timedelta
 from pathlib import Path
 from typing import Any, Dict, Iterator, List, Tuple
@@ -160,10 +159,10 @@ def find_hash_bin(path: str) -> str:
                     keys["bin-n"]
                 )
             },
-            roles=OrderedDict(),
+            roles={},
         ),
     ),
-    signatures=OrderedDict(),
+    signatures={},
 )
 
 # The hash bin generator yields an ordered list of incremental hash bin names
@@ -190,7 +189,7 @@ def find_hash_bin(path: str) -> str:
         signed=Targets(
             version=1, spec_version=SPEC_VERSION, expires=_in(7), targets={}
         ),
-        signatures=OrderedDict(),
+        signatures={},
     )
 
 # Add target file

requirements.txt

@@ -26,7 +26,7 @@
 # 1. Use this script to create a pinned requirements file for each Python
 #    version
 # ```
-# for v in 3.6 3.7 3.8 3.9; do
+# for v in 3.7 3.8 3.9; do
 #   mkvirtualenv tuf-env-${v} -p python${v};
 #   python3 -m pip install pip-tools;
 #   pip-compile --no-header -o requirements-${v}.txt requirements.txt;

setup.cfg

@@ -21,7 +21,6 @@ classifiers =
   Operating System :: MacOS :: MacOS X
   Operating System :: Microsoft :: Windows
   Programming Language :: Python :: 3
-  Programming Language :: Python :: 3.6
   Programming Language :: Python :: 3.7
   Programming Language :: Python :: 3.8
   Programming Language :: Python :: 3.9
@@ -37,7 +36,7 @@ packages = find:
 scripts =
   tuf/scripts/repo.py
   tuf/scripts/client.py
-python_requires = ~=3.6
+python_requires = ~=3.7
 install_requires =
   requests>=2.19.1
   securesystemslib>=0.20.0

tests/repository_simulator.py

@@ -47,7 +47,6 @@
 import logging
 import os
 import tempfile
-from collections import OrderedDict
 from dataclasses import dataclass, field
 from datetime import datetime, timedelta
 from typing import Dict, Iterator, List, Optional, Tuple
@@ -167,15 +166,15 @@ def _initialize(self) -> None:
         """Setup a minimal valid repository."""
 
         targets = Targets(1, SPEC_VER, self.safe_expiry, {}, None)
-        self.md_targets = Metadata(targets, OrderedDict())
+        self.md_targets = Metadata(targets, {})
 
         meta = {"targets.json": MetaFile(targets.version)}
         snapshot = Snapshot(1, SPEC_VER, self.safe_expiry, meta)
-        self.md_snapshot = Metadata(snapshot, OrderedDict())
+        self.md_snapshot = Metadata(snapshot, {})
 
         snapshot_meta = MetaFile(snapshot.version)
         timestamp = Timestamp(1, SPEC_VER, self.safe_expiry, snapshot_meta)
-        self.md_timestamp = Metadata(timestamp, OrderedDict())
+        self.md_timestamp = Metadata(timestamp, {})
 
         roles = {role_name: Role([], 1) for role_name in TOP_LEVEL_ROLE_NAMES}
         root = Root(1, SPEC_VER, self.safe_expiry, {}, roles, True)
@@ -185,7 +184,7 @@ def _initialize(self) -> None:
             root.add_key(role, key)
             self.add_signer(role, signer)
 
-        self.md_root = Metadata(root, OrderedDict())
+        self.md_root = Metadata(root, {})
         self.publish_root()
 
     def publish_root(self) -> None:
@@ -357,7 +356,7 @@ def add_delegation(
 
         # Create delegation
         if delegator.delegations is None:
-            delegator.delegations = Delegations({}, OrderedDict())
+            delegator.delegations = Delegations({}, {})
         # put delegation last by default
         delegator.delegations.roles[role.name] = role
 
@@ -368,7 +367,7 @@ def add_delegation(
 
         # Add metadata for the role
         if role.name not in self.md_delegates:
-            self.md_delegates[role.name] = Metadata(targets, OrderedDict())
+            self.md_delegates[role.name] = Metadata(targets, {})
 
     def write(self) -> None:
         """Dump current repository metadata to self.dump_dir

tuf/api/metadata.py

@@ -32,7 +32,6 @@
 import io
 import logging
 import tempfile
-from collections import OrderedDict
 from datetime import datetime
 from typing import (
     IO,
@@ -113,7 +112,7 @@ class Metadata(Generic[T]):
             signing the canonical serialized representation of 'signed'.
     """
 
-    def __init__(self, signed: T, signatures: "OrderedDict[str, Signature]"):
+    def __init__(self, signed: T, signatures: Dict[str, Signature]):
         self.signed: T = signed
         self.signatures = signatures
 
@@ -150,7 +149,7 @@ def from_dict(cls, metadata: Dict[str, Any]) -> "Metadata[T]":
             raise ValueError(f'unrecognized metadata type "{_type}"')
 
         # Make sure signatures are unique
-        signatures: "OrderedDict[str, Signature]" = OrderedDict()
+        signatures: Dict[str, Signature] = {}
         for sig_dict in metadata.pop("signatures"):
             sig = Signature.from_dict(sig_dict)
             if sig.keyid in signatures:
@@ -1211,7 +1210,7 @@ class Delegations:
     def __init__(
         self,
         keys: Dict[str, Key],
-        roles: "OrderedDict[str, DelegatedRole]",
+        roles: Dict[str, DelegatedRole],
         unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ):
         self.keys = keys
@@ -1233,7 +1232,7 @@ def from_dict(cls, delegations_dict: Dict[str, Any]) -> "Delegations":
         for keyid, key_dict in keys.items():
             keys_res[keyid] = Key.from_dict(keyid, key_dict)
         roles = delegations_dict.pop("roles")
-        roles_res: "OrderedDict[str, DelegatedRole]" = OrderedDict()
+        roles_res: Dict[str, DelegatedRole] = {}
         for role_dict in roles:
             new_role = DelegatedRole.from_dict(role_dict)
             if new_role.name in roles_res: