Added a pylint plugin to set django settings module (#26938)

* Added a pylint plugin to set django settings module according to the module on which pylint is ran

* Fix quality

Co-authored-by: Awais Qureshi <awais.qureshi@arbisoft.com>

pylint_django_settings.py

@@ -0,0 +1,58 @@
+from pylint.interfaces import IAstroidChecker
+from pylint.checkers import BaseChecker
+from pylint_django.checkers import ForeignKeyStringsChecker
+from pylint_plugin_utils import get_checker
+
+
+class ArgumentCompatibilityError(Exception):
+    pass
+
+
+class SetDjangoSettingsChecker(BaseChecker):
+    """
+    This isn't a checker, but setting django settings module when pylint command is ran.
+    This is to avoid 'django-not-configured' pylint warning
+
+    """
+    __implements__ = IAstroidChecker
+
+    name = 'set-django-settings'
+
+    msgs = {'R0991': ('bogus', 'bogus', 'bogus')}
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+    def open(self):
+        name_checker = get_checker(self.linter, ForeignKeyStringsChecker)
+        # pylint command should not run with modules from both cms and (lms, common) at once
+        cms_module = False
+        lms_module = False
+        common_module = False
+        for arg in self.linter.cmdline_parser.largs:
+            if arg.startswith('cms'):
+                cms_module = True
+            elif arg.startswith('lms'):
+                lms_module = True
+            elif arg.startswith('common'):
+                common_module = True
+
+        if cms_module and (lms_module or common_module):
+            # when cms module is present in pylint command, it can't be parired with (lms, common)
+            # as common and lms gives error with cms test settings
+            raise ArgumentCompatibilityError(
+                "Modules from both common and lms can't be paired with cms while running pylint"
+            )
+        elif cms_module:
+            # If a module from cms is present in pylint command arguments
+            # and ony other module from (openedx, pavelib) is present
+            # than test setting of cms is used
+            name_checker.config.django_settings_module = 'cms.envs.test'
+        else:
+            # If any module form (lms, common, openedx, pavelib) is present in
+            # pylint command arguments than test setting of lms is used
+            name_checker.config.django_settings_module = 'lms.envs.test'
+
+
+def register(linter):
+    linter.register_checker(SetDjangoSettingsChecker(linter))

pylintrc

@@ -72,7 +72,7 @@
 [MASTER]
 ignore = ,.git,.tox,migrations,node_modules,.pycharm_helpers
 persistent = yes
-load-plugins = edx_lint.pylint,pylint_django,pylint_celery
+load-plugins = edx_lint.pylint,pylint_django_settings,pylint_django,pylint_celery
 
 [MESSAGES CONTROL]
 enable =