module_helper.py Breakdown (#2393)

* break down of module_helper into smaller pieces, keeping compatibility

* removed abc.ABC (py3 only) from code + fixed reference to vars.py

* multiple changes:

- mh.base - moved more functionalities to ModuleHelperBase
- mh.mixins.(cmd, state) - CmdMixin no longer inherits from ModuleHelperBase
- mh.mixins.deps - DependencyMixin now overrides run() method to test dependency
- mh.mixins.vars - created class VarsMixin
- mh.module_helper - moved functions to base class, added VarsMixin
- module_helper - importing AnsibleModule as well, for backward compatibility in test

* removed unnecessary __all__

* make pylint happy

* PR adjustments + bot config + changelog frag

* Update plugins/module_utils/mh/module_helper.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update plugins/module_utils/mh/module_helper.py

Co-authored-by: Felix Fontein <felix@fontein.de>

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/module_utils/mh/base.py

@@ -0,0 +1,56 @@
+# -*- coding: utf-8 -*-
+# (c) 2020, Alexei Znamensky <russoz@gmail.com>
+# Copyright: (c) 2020, Ansible Project
+# Simplified BSD License (see licenses/simplified_bsd.txt or https://opensource.org/licenses/BSD-2-Clause)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+from ansible.module_utils.basic import AnsibleModule
+from ansible_collections.community.general.plugins.module_utils.mh.exceptions import ModuleHelperException as _MHE
+from ansible_collections.community.general.plugins.module_utils.mh.deco import module_fails_on_exception
+
+
+class ModuleHelperBase(object):
+    module = None
+    ModuleHelperException = _MHE
+
+    def __init__(self, module=None):
+        self._changed = False
+
+        if module:
+            self.module = module
+
+        if not isinstance(self.module, AnsibleModule):
+            self.module = AnsibleModule(**self.module)
+
+    def __init_module__(self):
+        pass
+
+    def __run__(self):
+        raise NotImplementedError()
+
+    def __quit_module__(self):
+        pass
+
+    @property
+    def changed(self):
+        return self._changed
+
+    @changed.setter
+    def changed(self, value):
+        self._changed = value
+
+    def has_changed(self):
+        raise NotImplementedError()
+
+    @property
+    def output(self):
+        raise NotImplementedError()
+
+    @module_fails_on_exception
+    def run(self):
+        self.__init_module__()
+        self.__run__()
+        self.__quit_module__()
+        self.module.exit_json(changed=self.has_changed(), **self.output)