refactor(lint): Work on PyLint rule W0612 (unused-variable)

Thank you to Keith Bates (@dnerever) for this contribution.

Related to #1755 
---------

Co-authored-by: buhtz <c.buhtz@posteo.jp>

common/config.py

@@ -1602,7 +1602,7 @@ def olderThan(self, time, value, unit):
                                  - datetime.timedelta(weeks = value - 1)
         elif unit <= self.MONTH:
             firstDay = now.date() - datetime.timedelta(days = now.date().day + 1)
-            for i in range(value - 1):
+            for _ in range(value - 1):
                 if firstDay.month == 1:
                     firstDay = firstDay.replace(month = 12, year = firstDay.year - 1)
                 else:

common/schedule.py

@@ -175,7 +175,7 @@ def is_cron_running():
 
     with subprocess.Popen(['ps', '-eo', 'comm'], stdout=subprocess.PIPE) as ps:
         try:
-            grep = subprocess.run(
+            subprocess.run(
                 ['grep', '--ignore-case', 'cron'],
                 stdin=ps.stdout,
                 stdout=subprocess.PIPE,

common/sshtools.py

@@ -840,7 +840,7 @@ def maxArg():
                                         stdout=subprocess.PIPE,
                                         stderr=subprocess.PIPE,
                                         universal_newlines=True)
-                out, err = proc.communicate()
+                err = proc.communicate()[1]
 
                 if err or proc.returncode:
                     logger.debug(f'rsync command returned error: {err}', self)
@@ -1057,7 +1057,7 @@ def sshKeyGen(keyfile):
                             stderr=subprocess.PIPE,
                             universal_newlines=True)
 
-    out, err = proc.communicate()
+    err = proc.communicate()[1]
 
     if proc.returncode:
         logger.error('Failed to create a new ssh-key: {}'.format(err))
@@ -1178,7 +1178,7 @@ def sshCopyId(
                                                    # backintime-askpass
                             universal_newlines=True)
 
-    out, err = proc.communicate()
+    err = proc.communicate()[1]
 
     if proc.returncode:
         logger.error('Failed to copy ssh-key "{}" to "{}@{}": [{}] {}'

common/test/test_applicationinstance.py

@@ -209,7 +209,7 @@ def test_non_existing_process(self):
         self.assertTrue(self.app_instance.check())
 
     def test_leftover_empty_lockfile(self):
-        with open(self.file_name, 'wt')as f:
+        with open(self.file_name, 'wt') as f:
             pass
         self.assertTrue(self.app_instance.check())
 

common/test/test_lint.py

@@ -89,30 +89,30 @@ def test_with_pylint(self):
             'E0401',  # import-error
             'E0602',  # undefined-variable
             'E1101',  # no-member
-            'W0311',  # bad-indentation
             'I0021',  # useless-suppression
+            'W0123',  # eval-used
+            'W0237',  # arguments-renamed
+            'W0311',  # bad-indentation
+            'W0404',  # reimported
             'W0611',  # unused-import
+            # 'W0612',  # unused-variable
+            'W0614',  # unused-wildcard-import
+            'W0707',  # raise-missing-from
             'W1301',  # unused-format-string-key
             'W1401',  # anomalous-backslash-in-string (invalid escape sequence)
             'W1515',  # forgotten-debug-statement
+            'W4902',  # deprecated-method
+            'W4904',  # deprecated-class
             'R0201',  # no-self-use
             'R0202',  # no-classmethod-decorator
             'R0203',  # no-staticmethod-decorator
-            'W0404',  # reimported
-            'W4902',  # deprecated-method
-            'W4904',  # deprecated-class
-            'W0614',  # unused-wildcard-import
-            'W0237',  # arguments-renamed
-            'W0123',  # eval-used
-            'W0707',  # raise-missing-from
 
             # Enable asap. This list is a selection of existing (not all!)
             # problems currently existing in the BIT code base. Quite easy to fix
             # because their count is low.
             # 'R0801',  # duplicate-code
             # 'W0221',  # arguments-differ
             # 'W0603',  # global-statement
-            # 'W0612',  # unused-variable
         ]
 
         cmd.append('--enable=' + ','.join(err_codes))

common/test/test_plugin_usercallback.py

@@ -177,7 +177,6 @@ def _extract_callback_responses(cls, output):
         callback_responses = []
 
         for line in response_lines:
-            to_eval = line[line.index("'")+1:line.rindex("'")]
 
             callback_responses.append(
                 literal_eval(line[line.index("'")+1:line.rindex("'")])

common/tools.py

@@ -28,7 +28,6 @@
 import gzip
 import locale
 import gettext
-from collections.abc import MutableSet
 import hashlib
 import ipaddress
 import atexit
@@ -2704,7 +2703,7 @@ def stop(self):
             return
 
         # Get the pid from the pidfile
-        pid, procname = self.appInstance.readPidFile()
+        pid = self.appInstance.readPidFile()[0]
 
         if not pid:
             message = "pidfile %s does not exist. Daemon not running?\n"
@@ -2740,7 +2739,7 @@ def reload(self):
             return
 
         # Get the pid from the pidfile
-        pid, procname = self.appInstance.readPidFile()
+        pid = self.appInstance.readPidFile()[0]
 
         if not pid:
             message = "pidfile %s does not exist. Daemon not running?\n"

qt/test/test_lint.py

@@ -89,10 +89,9 @@ def test_with_pylint(self):
             'E0401',  # import-error
             'E0602',  # undefined-variable
             'E1101',  # no-member
+            'I0021',  # useless-suppression
             'W0311',  # bad-indentation
             'W0611',  # unused-import
-            'I0021',  # useless-suppression
-            # 'W0611',  # unused-import
             'W1301',  # unused-format-string-key
             'W1401',  # anomalous-backslash-in-string (invalid escape sequence)
             'W1515',  # forgotten-debug-statement