module_helper.py Breakdown (#2393) (#2492)

* 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>
(cherry picked from commit d22dd5056e)

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

plugins/module_utils/mh/deco.py

@@ -0,0 +1,54 @@
+# -*- 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
+
+import traceback
+from functools import wraps
+
+from ansible_collections.community.general.plugins.module_utils.mh.exceptions import ModuleHelperException
+
+
+def cause_changes(on_success=None, on_failure=None):
+
+    def deco(func):
+        if on_success is None and on_failure is None:
+            return func
+
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            try:
+                self = args[0]
+                func(*args, **kwargs)
+                if on_success is not None:
+                    self.changed = on_success
+            except Exception:
+                if on_failure is not None:
+                    self.changed = on_failure
+                raise
+
+        return wrapper
+
+    return deco
+
+
+def module_fails_on_exception(func):
+    @wraps(func)
+    def wrapper(self, *args, **kwargs):
+        try:
+            func(self, *args, **kwargs)
+        except SystemExit:
+            raise
+        except ModuleHelperException as e:
+            if e.update_output:
+                self.update_output(e.update_output)
+            self.module.fail_json(msg=e.msg, exception=traceback.format_exc(),
+                                  output=self.output, vars=self.vars.output(), **self.output)
+        except Exception as e:
+            msg = "Module failed with exception: {0}".format(str(e).strip())
+            self.module.fail_json(msg=msg, exception=traceback.format_exc(),
+                                  output=self.output, vars=self.vars.output(), **self.output)
+    return wrapper