Start linting the examples folder

The examples folder currently contains a repository example and it's
good if we start linting its content and as a result add type
annotations.

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

examples/repo_example/basic_repo.py

@@ -28,6 +28,7 @@
 from collections import OrderedDict
 from datetime import datetime, timedelta
 from pathlib import Path
+from typing import Any, Dict
 
 from securesystemslib.keys import generate_ed25519_key
 from securesystemslib.signer import SSlibSigner
@@ -48,7 +49,7 @@
 from tuf.api.serialization.json import JSONSerializer
 
 
-def _in(days):
+def _in(days: float) -> datetime:
     """Adds 'days' to now and returns datetime object w/o microseconds."""
     return datetime.utcnow().replace(microsecond=0) + timedelta(days=days)
 
@@ -89,8 +90,8 @@ def _in(days):
 
 # Define containers for role objects and cryptographic keys created below. This
 # allows us to sign and write metadata in a batch more easily.
-roles = {}
-keys = {}
+roles: Dict[str, Metadata] = {}
+keys: Dict[str, Dict[str, Any]] = {}
 
 
 # Targets (integrity)
@@ -117,7 +118,7 @@ def _in(days):
 local_path = Path(__file__).resolve()
 target_path = f"{local_path.parts[-2]}/{local_path.parts[-1]}"
 
-target_file_info = TargetFile.from_file(target_path, local_path)
+target_file_info = TargetFile.from_file(target_path, str(local_path))
 roles["targets"].signed.targets[target_path] = target_file_info
 
 # Snapshot (consistency)
@@ -332,7 +333,7 @@ def _in(days):
 del roles["targets"].signed.targets[target_path]
 
 # Increase expiry (delegators should be less volatile)
-roles["targets"].expires = _in(365)
+roles["targets"].signed.expires = _in(365)
 
 
 # Snapshot + Timestamp + Sign + Persist

pyproject.toml

@@ -79,7 +79,8 @@ show_error_codes = "True"
 files = [
   "tuf/api/",
   "tuf/ngclient",
-  "tuf/exceptions.py"
+  "tuf/exceptions.py",
+  "examples/",
 ]
 
 [[tool.mypy.overrides]]

tox.ini

@@ -40,9 +40,9 @@ commands =
 changedir = {toxinidir}
 commands =
     # Use different configs for new (tuf/api/*) and legacy code
-    black --check --diff tuf/api tuf/ngclient
-    isort --check --diff tuf/api tuf/ngclient
-    pylint -j 0 tuf/api tuf/ngclient --rcfile=pyproject.toml
+    black --check --diff tuf/api tuf/ngclient examples
+    isort --check --diff tuf/api tuf/ngclient examples
+    pylint -j 0 tuf/api tuf/ngclient --rcfile=pyproject.toml examples
 
     # NOTE: Contrary to what the pylint docs suggest, ignoring full paths does
     # work, unfortunately each subdirectory has to be ignored explicitly.