fixed many mypy issues

config.py

@@ -22,21 +22,27 @@ class Config:
         self.config = ArgumentsParser().parser.config
     
     @cached_property
-    def root(self) -> etree.ElementTree:
+    def root(self) -> etree._ElementTree:
         return etree.parse(self.basepath / self.config)
     
     @cached_property
-    def app_root(self) -> etree.Element:
-        return self.root.xpath('/cpuGovernorAutoAdjust').pop()
+    def app_root(self) -> etree._Element:
+        _tree = self.root.xpath('/cpuGovernorAutoAdjust')
+        assert isinstance(_tree, list) and len(_tree) == 1, "main config section cpuGovernorAutoAdjust not found"
+        ret_val = _tree.pop()
+        assert isinstance(ret_val, etree._Element), "Unexpected error has occurred, cpuGovernorAutoAdjust is not of type etree._Element"
+    
+        return ret_val
     
     @cached_property
     def loglevel(self) -> str:
-        value = self.app_root.xpath('logLevel').pop().text.upper()
-        _loglevels = ", ".join(logging.getLevelNamesMapping().keys())
+        _loglevel = self._get_single_text_value_from_xpath('logLevel')
+        value = _loglevel.upper()
+        _available_loglevels = ", ".join(logging.getLevelNamesMapping().keys())
         if value not in logging.getLevelNamesMapping().keys():
             raise ValueError(
                 "logLevel can only contain one of these values: "
-                f"{_loglevels}"
+                f"{_available_loglevels}"
             )
         return value
     
@@ -46,7 +52,8 @@ class Config:
     
     @cached_property
     def testmode(self) -> bool:
-        value = self.app_root.xpath('testMode').pop().text.lower()
+        _testmode = self._get_single_text_value_from_xpath('testMode')
+        value = _testmode.lower()
         if value is None:
             self.log.warning("testMode not set in config")
         if value not in ['true', 'false']:
@@ -56,11 +63,11 @@ class Config:
     @cached_property
     def triggertuples(self) -> list[TriggerTuple]:
         ret_val = []
-        _triggers = self.app_root.xpath('triggers/trigger')
-        for trigger in _triggers:
-            name = trigger.xpath('name').pop().text
-            interval_in_seconds = trigger.xpath('intervalInSeconds').pop().text
-            governor = trigger.xpath('governor').pop().text
+        _trigger_elements = self._get_multiple_elements_by_xpath('triggers/trigger')
+        for trigger_elem in _trigger_elements:
+            name = self._get_single_text_value_from_xpath('name', trigger_elem)
+            interval_in_seconds = self._get_single_text_value_from_xpath('intervalInSeconds', trigger_elem)
+            governor = self._get_single_text_value_from_xpath('governor', trigger_elem)
             _new_trigger = TriggerTuple(
                     name=name,
                     interval_in_seconds=int(interval_in_seconds),
@@ -79,3 +86,26 @@ class Config:
         if ret_val is None:
             self.log.error("trigger not found: %s", ret_val)
         return ret_val
+    
+    def _get_single_text_value_from_xpath(self, xpath_str: str, element: Optional[etree._Element] = None) -> str:
+        _elem = self._get_single_element_by_xpath(xpath_str, element)
+        value = _elem.text
+        assert isinstance(value, str)
+        return value
+    
+    def _get_single_element_by_xpath(self, xpath_str: str, element: Optional[etree._Element] = None) -> etree._Element:
+        if element is None:
+            element = self.app_root
+        _list_of_elements = element.xpath(xpath_str)
+        assert isinstance(_list_of_elements, list) and len(_list_of_elements) == 1, f"config section {xpath_str} not found"
+        _elem = _list_of_elements.pop()
+        assert isinstance(_elem, etree._Element)
+        return _elem
+    
+    def _get_multiple_elements_by_xpath(self, xpath_str: str, element: Optional[etree._Element] = None) -> list[etree._Element]:
+        if element is None:
+            element = self.app_root
+        _list_of_elements = element.xpath(xpath_str)
+        assert isinstance(_list_of_elements, list) and len(_list_of_elements) >= 1, f"config section {xpath_str} not found"
+        assert all(isinstance(_elem, etree._Element) for _elem in _list_of_elements)
+        return _list_of_elements  # type: ignore