tests: fix get_level logic in deprecated_rules and optimize test_rules execution

Author: Shaivarth

tests/deprecated_rules.py

@@ -24,7 +24,7 @@
 
 
 def get_level(rule):
-    return rule.level if rule.status else SigmaLevel.MEDIUM
+    return rule.level if rule.level else SigmaLevel.MEDIUM
 
 
 def get_modified_time(rule):

tests/test_rules.py

@@ -11,6 +11,8 @@
 import yaml
 import re
 import string
+import copy
+import functools
 
 # from attackcti import attack_client
 from colorama import init
@@ -62,13 +64,26 @@ class TestRules(unittest.TestCase):
         "rules-compliance",
     ]
 
-    # Helper functions
-    def yield_next_rule_file_path(self, path_to_rules: list) -> str:
-        for path_ in path_to_rules:
+    @classmethod
+    def setUpClass(cls):
+        cls._rule_file_paths = []
+        for path_ in cls.path_to_rules:
             for root, _, files in os.walk(path_):
                 for file in files:
                     if file.endswith(".yml"):
-                        yield os.path.join(root, file)
+                        cls._rule_file_paths.append(os.path.join(root, file))
+
+    # Helper functions
+    def yield_next_rule_file_path(self, path_to_rules: list) -> str:
+        if path_to_rules == self.path_to_rules and hasattr(self, "_rule_file_paths"):
+            for file_path in self._rule_file_paths:
+                yield file_path
+        else:
+            for path_ in path_to_rules:
+                for root, _, files in os.walk(path_):
+                    for file in files:
+                        if file.endswith(".yml"):
+                            yield os.path.join(root, file)
 
     def get_rule_part(self, file_path: str, part_name: str):
         yaml_dicts = self.get_rule_yaml(file_path)
@@ -78,15 +93,14 @@ def get_rule_part(self, file_path: str, part_name: str):
 
         return None
 
-    def get_rule_yaml(self, file_path: str) -> dict:
-        data = []
-
+    @staticmethod
+    @functools.lru_cache(maxsize=None)
+    def _read_rule_yaml(file_path: str) -> tuple:
         with open(file_path, encoding="utf-8") as f:
-            yaml_parts = yaml.safe_load_all(f)
-            for part in yaml_parts:
-                data.append(part)
+            return tuple(yaml.safe_load_all(f))
 
-        return data
+    def get_rule_yaml(self, file_path: str) -> dict:
+        return [copy.deepcopy(part) for part in self._read_rule_yaml(file_path)]
 
     # Tests
     def test_legal_trademark_violations(self):
@@ -1146,7 +1160,7 @@ def test_re_invalid_escapes(self):
         MAX_DEPTH = 3
 
         def create_escape_allow_list():
-            """
+            r"""
             Create a list of characters that are allowed to be escaped.
             1. Based on string.punctuation chars that would already be escaped by re.escape()
             2. Followed by special chars like '\n', '\t', '\[0-9]' etc.