twister: Refactor python module to follow PEP8 rules

Incremental refactoring.
Fix PEP8 issues to make ruff green for config_parser.py module.
Add __init__.py to twister directory to make it a proper python package,
and make modules importable.

Signed-off-by: Lukasz Fundakowski <lukasz.fundakowski@nordicsemi.no>

.ruff-excludes.toml

@@ -828,14 +828,6 @@
     "I001",     # https://docs.astral.sh/ruff/rules/unsorted-imports
     "UP026",    # https://docs.astral.sh/ruff/rules/deprecated-mock-import
 ]
-"./scripts/tests/twister/test_config_parser.py" = [
-    "B017",     # https://docs.astral.sh/ruff/rules/assert-raises-exception
-    "B033",     # https://docs.astral.sh/ruff/rules/duplicate-value
-    "E501",     # https://docs.astral.sh/ruff/rules/line-too-long
-    "I001",     # https://docs.astral.sh/ruff/rules/unsorted-imports
-    "SIM117",   # https://docs.astral.sh/ruff/rules/multiple-with-statements
-    "UP026",    # https://docs.astral.sh/ruff/rules/deprecated-mock-import
-]
 "./scripts/tests/twister/test_data/mixins/test_to_ignore.py" = [
     "B011",     # https://docs.astral.sh/ruff/rules/assert-false
 ]

scripts/pylib/twister/__init__.py

@@ -0,0 +1,2 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0

scripts/pylib/twister/twisterlib/__init__.py

@@ -0,0 +1,2 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0

scripts/pylib/twister/twisterlib/config_parser.py

@@ -5,18 +5,21 @@
 
 import copy
 import warnings
+from typing import Any
 
 import scl
 from twisterlib.error import ConfigurationError
 
 
-def extract_fields_from_arg_list(target_fields: set, arg_list: str | list):
+def extract_fields_from_arg_list(
+    target_fields: set, arg_list: str | list
+ ) -> tuple[dict[str, list[str]], list[str]]:
     """
     Given a list of "FIELD=VALUE" args, extract values of args with a
     given field name and return the remaining args separately.
     """
-    extracted_fields = {f : list() for f in target_fields}
-    other_fields = []
+    extracted_fields: dict[str, list[str]] = {f: list() for f in target_fields}
+    other_fields: list[str] = []
 
     if isinstance(arg_list, str):
         args = arg_list.strip().split()
@@ -39,11 +42,13 @@ def extract_fields_from_arg_list(target_fields: set, arg_list: str | list):
 
     return extracted_fields, other_fields
 
+
 class TwisterConfigParser:
     """Class to read testsuite yaml files with semantic checking
     """
 
-    testsuite_valid_keys = {"tags": {"type": "set", "required": False},
+    testsuite_valid_keys: dict[str, dict[str, Any]] = {
+        "tags": {"type": "set", "required": False},
         "type": {"type": "str", "default": "integration"},
         "extra_args": {"type": "list"},
         "extra_configs": {"type": "list"},
@@ -85,18 +90,18 @@ class TwisterConfigParser:
         "sysbuild": {"type": "bool", "default": False}
     }
 
-    def __init__(self, filename, schema):
+    def __init__(self, filename: str, schema: dict[str, Any]) -> None:
         """Instantiate a new TwisterConfigParser object
 
         @param filename Source .yaml file to read
         """
-        self.data = {}
         self.schema = schema
         self.filename = filename
-        self.scenarios = {}
-        self.common = {}
+        self.data: dict[str, Any] = {}
+        self.scenarios: dict[str, Any] = {}
+        self.common: dict[str, Any] = {}
 
-    def load(self):
+    def load(self) -> dict[str, Any]:
         data = scl.yaml_load_verify(self.filename, self.schema)
         self.data = data
 
@@ -106,7 +111,7 @@ class TwisterConfigParser:
             self.common = self.data['common']
         return data
 
-    def _cast_value(self, value, typestr):
+    def _cast_value(self, value: Any, typestr: str) -> Any:
         if typestr == "str":
             return value.strip()
 
@@ -142,7 +147,7 @@ class TwisterConfigParser:
         else:
             raise ConfigurationError(self.filename, f"unknown type '{value}'")
 
-    def get_scenario(self, name):
+    def get_scenario(self, name: str) -> dict[str, Any]:
         """Get a dictionary representing the keys/values within a scenario
 
         @param name The scenario in the .yaml file to retrieve data from
@@ -152,10 +157,10 @@ class TwisterConfigParser:
 
         # "CONF_FILE", "OVERLAY_CONFIG", and "DTC_OVERLAY_FILE" fields from each
         # of the extra_args lines
-        extracted_common = {}
-        extracted_testsuite = {}
+        extracted_common: dict = {}
+        extracted_testsuite: dict = {}
 
-        d = {}
+        d: dict[str, Any] = {}
         for k, v in self.common.items():
             if k == "extra_args":
                 # Pull out these fields and leave the rest