fix: import the typing names the annotations use

Dict, List and Optional were used in 30 annotations without an import;
from __future__ import annotations kept that from failing until
something resolved them (typing.get_type_hints raised NameError).

Closes #29

napalm_linux/linux.py

@@ -23,7 +23,7 @@ import logging
 import re
 import socket
 from shlex import quote as _shlex_quote
-from typing import Any
+from typing import Any, Dict, List, Optional
 
 from netmiko import ConnectHandler
 from netmiko.exceptions import (

tests/test_fix_templates.py

@@ -180,3 +180,14 @@ def test_run_device_action_is_gone():
         "_action_apt_update_upgrade",
     ):
         assert not hasattr(LinuxDriver, name), name
+
+
+def test_every_annotation_resolves():
+    """``Dict``, ``List`` and ``Optional`` were used without being imported (#29);
+    ``from __future__ import annotations`` hid it until something resolved them."""
+    import inspect
+    import typing
+
+    for name, member in inspect.getmembers(LinuxDriver, inspect.isfunction):
+        if member.__module__ == "napalm_linux.linux":
+            typing.get_type_hints(member)