Adding module_utils/module_helper.py + big revamp in xfconf.py to use it (#1322) (#1336)

* Big revamp in xfconf.py

- added plugin/module_utils/module_helper.py
  - scaffold class for writing modules, beyond standard AnsibleModule
  - automatic capture of exceptions
  - easier dependency testing
  - StateMixin to easily handle different behaviours for 'state' param
  - CmdMixin to easily run external commands
- adapted test_xfconf.py
  - the args for run_command are now lists instead of a string
  - value and previous_value were not being tested before (because xfconf wasn't filling results - see below)
  - added more tests: setting value to previous_value, getting non-existent property
- rewritten xfconf module, keeping the same results
  - original module posted results as ansible_facts, this version still does it for compatibility, but also adds to the module result

* Added suggestions from the PR

* Added russoz as maintainer for the module_utils/module_helper.py file

* Formatting using printf-style requires special treatment

Strings not containing substitution tokens must work as well.

* Tidied up variables in module definition

* Tests with ArgFormat and DependencyCtxMgr

* pytest parameters must be in the same order, it seems

* improved testing for the DependencyCtxMgr

* fixed test for older pythons

* Moved changed property to improve readability

* Added testcase for state: absent and adjusted xfconf after it

* Fixed param name environ_update in run_command()

* added changelog fragment

* fixed tests after run_command param change

(cherry picked from commit e3fcc7de2a)

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

.github/BOTMETA.yml

@@ -166,6 +166,9 @@ files:
   $module_utils/memset.py:
     maintainers: glitchcrab
     labels: cloud memset
+  $module_utils/module_helper.py:
+    maintainers: russoz
+    labels: module_helper
   $module_utils/net_tools/nios/api.py:
     maintainers: $team_networking sganesh-infoblox
     labels: infoblox networking

changelogs/fragments/1322-module_helper_and_xfconf.yaml

@@ -0,0 +1,5 @@
+minor_changes:
+  - module_helper - added ModuleHelper class and a couple of convenience tools for module developers (https://github.com/ansible-collections/community.general/pull/1322).
+bugfixes:
+  - xfconf - xfconf no longer passing the command args as a string, but rather as a list (https://github.com/ansible-collections/community.general/issues/1328).
+  - xfconf - parameter ``value`` no longer required for state ``absent`` (https://github.com/ansible-collections/community.general/issues/1329).

plugins/module_utils/module_helper.py

@@ -0,0 +1,302 @@
+# -*- coding: utf-8 -*-
+# Copyright: (c) 2018, 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 functools import partial, wraps
+import traceback
+
+from ansible.module_utils.basic import AnsibleModule
+
+
+class ArgFormat(object):
+    """
+    Argument formatter
+    """
+    BOOLEAN = 0
+    PRINTF = 1
+    FORMAT = 2
+
+    @staticmethod
+    def stars_deco(num):
+        if num == 1:
+            def deco(f):
+                return lambda v: f(*v)
+            return deco
+        elif num == 2:
+            def deco(f):
+                return lambda v: f(**v)
+            return deco
+
+        return lambda f: f
+
+    def __init__(self, name, fmt=None, style=FORMAT, stars=0):
+        """
+        Creates a new formatter
+        :param name: Name of the argument to be formatted
+        :param fmt: Either a str to be formatted (using or not printf-style) or a callable that does that
+        :param style: Whether arg_format (as str) should use printf-style formatting.
+                             Ignored if arg_format is None or not a str (should be callable).
+        :param stars: A int with 0, 1 or 2 value, indicating to formatting the value as: value, *value or **value
+        """
+        def printf_fmt(_fmt, v):
+            try:
+                return [_fmt % v]
+            except TypeError as e:
+                if e.args[0] != 'not all arguments converted during string formatting':
+                    raise
+                return [_fmt]
+
+        _fmts = {
+            ArgFormat.BOOLEAN: lambda _fmt, v: ([_fmt] if bool(v) else []),
+            ArgFormat.PRINTF: printf_fmt,
+            ArgFormat.FORMAT: lambda _fmt, v: [_fmt.format(v)],
+        }
+
+        self.name = name
+        self.stars = stars
+
+        if fmt is None:
+            fmt = "{0}"
+            style = ArgFormat.FORMAT
+
+        if isinstance(fmt, str):
+            func = _fmts[style]
+            self.arg_format = partial(func, fmt)
+        elif isinstance(fmt, list) or isinstance(fmt, tuple):
+            self.arg_format = lambda v: [_fmts[style](f, v)[0] for f in fmt]
+        elif hasattr(fmt, '__call__'):
+            self.arg_format = fmt
+        else:
+            raise TypeError('Parameter fmt must be either: a string, a list/tuple of '
+                            'strings or a function: type={0}, value={1}'.format(type(fmt), fmt))
+
+        if stars:
+            self.arg_format = (self.stars_deco(stars))(self.arg_format)
+
+    def to_text(self, value):
+        func = self.arg_format
+        return [str(p) for p in func(value)]
+
+
+def cause_changes(func, on_success=True, on_failure=False):
+    @wraps(func)
+    def wrapper(self, *args, **kwargs):
+        try:
+            func(*args, **kwargs)
+            if on_success:
+                self.changed = True
+        except Exception as e:
+            if on_failure:
+                self.changed = True
+            raise
+    return wrapper
+
+
+def module_fails_on_exception(func):
+    @wraps(func)
+    def wrapper(self, *args, **kwargs):
+        try:
+            func(self, *args, **kwargs)
+        except SystemExit:
+            raise
+        except Exception as e:
+            self.vars.msg = "Module failed with exception: {0}".format(str(e).strip())
+            self.vars.exception = traceback.format_exc()
+            self.module.fail_json(changed=False, msg=self.vars.msg, exception=self.vars.exception, output=self.output, vars=self.vars)
+    return wrapper
+
+
+class DependencyCtxMgr(object):
+    def __init__(self, name, msg=None):
+        self.name = name
+        self.msg = msg
+        self.has_it = False
+        self.exc_type = None
+        self.exc_val = None
+        self.exc_tb = None
+
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.has_it = exc_type is None
+        self.exc_type = exc_type
+        self.exc_val = exc_val
+        self.exc_tb = exc_tb
+        return not self.has_it
+
+    @property
+    def text(self):
+        return self.msg or str(self.exc_val)
+
+
+class ModuleHelper(object):
+    _dependencies = []
+    module = {}
+    facts_name = None
+
+    class AttrDict(dict):
+        def __getattr__(self, item):
+            return self[item]
+
+    def __init__(self, module=None):
+        self.vars = ModuleHelper.AttrDict()
+        self.output_dict = dict()
+        self.facts_dict = dict()
+        self._changed = False
+
+        if module:
+            self.module = module
+
+        if not isinstance(module, AnsibleModule):
+            self.module = AnsibleModule(**self.module)
+
+    def update_output(self, **kwargs):
+        if kwargs:
+            self.output_dict.update(kwargs)
+
+    def update_facts(self, **kwargs):
+        if kwargs:
+            self.facts_dict.update(kwargs)
+
+    def __init_module__(self):
+        pass
+
+    def __run__(self):
+        raise NotImplementedError()
+
+    @property
+    def changed(self):
+        return self._changed
+
+    @changed.setter
+    def changed(self, value):
+        self._changed = value
+
+    @property
+    def output(self):
+        result = dict(self.vars)
+        result.update(self.output_dict)
+        if self.facts_name:
+            result['ansible_facts'] = {self.facts_name: self.facts_dict}
+        return result
+
+    @module_fails_on_exception
+    def run(self):
+        self.fail_on_missing_deps()
+        self.__init_module__()
+        self.__run__()
+        self.module.exit_json(changed=self.changed, **self.output_dict)
+
+    @classmethod
+    def dependency(cls, name, msg):
+        cls._dependencies.append(DependencyCtxMgr(name, msg))
+        return cls._dependencies[-1]
+
+    def fail_on_missing_deps(self):
+        for d in self._dependencies:
+            if not d.has_it:
+                self.module.fail_json(changed=False,
+                                      exception=d.exc_val.__traceback__.format_exc(),
+                                      msg=d.text,
+                                      **self.output_dict)
+
+
+class StateMixin(object):
+    state_param = 'state'
+    default_state = None
+
+    def _state(self):
+        state = self.module.params.get(self.state_param)
+        return self.default_state if state is None else state
+
+    def __run__(self):
+        state = self._state()
+        self.vars.state = state
+
+        # resolve aliases
+        if state not in self.module.params:
+            aliased = [name for name, param in self.module.argument_spec.items() if state in param.get('aliases', [])]
+            if aliased:
+                state = aliased[0]
+                self.vars.effective_state = state
+
+        method = "state_{0}".format(state)
+        if not hasattr(self, method):
+            return self.__state_fallback__()
+        func = getattr(self, method)
+        return func()
+
+    def __state_fallback__(self):
+        raise ValueError("Cannot find method for state: {0}".format(self._state()))
+
+
+class CmdMixin(object):
+    """
+    Mixin for mapping module options to running a CLI command with its arguments.
+    """
+    command = None
+    command_args_formats = dict()
+    check_rc = False
+    force_lang = "C"
+
+    @property
+    def module_formats(self):
+        result = {}
+        for param in self.module.params.keys():
+            result[param] = ArgFormat(param)
+        return result
+
+    @property
+    def custom_formats(self):
+        result = {}
+        for param, fmt_spec in self.command_args_formats.items():
+            result[param] = ArgFormat(param, **fmt_spec)
+        return result
+
+    def _calculate_args(self, extra_params=None, params=None):
+        def add_arg_formatted_param(_cmd_args, arg_format, _value):
+            args = [x for x in arg_format.to_text(_value)]
+            return _cmd_args + args
+
+        def find_format(_param):
+            return self.custom_formats.get(_param, self.module_formats.get(_param))
+
+        extra_params = extra_params or dict()
+        cmd_args = [self.module.get_bin_path(self.command)]
+        param_list = params if params else self.module.params.keys()
+
+        for param in param_list:
+            if param in self.module.argument_spec:
+                if param not in self.module.params:
+                    continue
+                fmt = find_format(param)
+                value = self.module.params[param]
+            else:
+                if param not in extra_params:
+                    continue
+                fmt = find_format(param)
+                value = extra_params[param]
+            self.cmd_args = cmd_args
+            cmd_args = add_arg_formatted_param(cmd_args, fmt, value)
+
+        return cmd_args
+
+    def process_command_output(self, rc, out, err):
+        return rc, out, err
+
+    def run_command(self, extra_params=None, params=None, *args, **kwargs):
+        self.vars['cmd_args'] = self._calculate_args(extra_params, params)
+        env_update = kwargs.get('environ_update', {})
+        check_rc = kwargs.get('check_rc', self.check_rc)
+        if self.force_lang:
+            env_update.update({'LANGUAGE': self.force_lang})
+            self.update_output(force_lang=self.force_lang)
+        rc, out, err = self.module.run_command(self.vars['cmd_args'],
+                                               environ_update=env_update,
+                                               check_rc=check_rc, *args, **kwargs)
+        self.update_output(rc=rc, stdout=out, stderr=err)
+        return self.process_command_output(rc, out, err)

plugins/modules/system/xfconf.py

@@ -7,7 +7,6 @@
 from __future__ import absolute_import, division, print_function
 __metaclass__ = type
 
-
 DOCUMENTATION = '''
 module: xfconf
 author:
@@ -112,195 +111,149 @@ RETURN = '''
     sample: "96"
 '''
 
-import traceback
+from ansible_collections.community.general.plugins.module_utils.module_helper import (
+    ModuleHelper, CmdMixin, StateMixin, ArgFormat
+)
 
-from ansible.module_utils.basic import AnsibleModule
-from ansible.module_utils.six.moves import shlex_quote
+
+def fix_bool(value):
+    vl = value.lower()
+    return vl if vl in ("true", "false") else value
+
+
+@ArgFormat.stars_deco(1)
+def values_fmt(values, value_types):
+    result = []
+    for value, value_type in zip(values, value_types):
+        if value_type == 'bool':
+            value = fix_bool(value)
+        result.append('--type')
+        result.append('{0}'.format(value_type))
+        result.append('--set')
+        result.append('{0}'.format(value))
+    return result
 
 
 class XFConfException(Exception):
     pass
 
 
-class XFConfProperty(object):
-    SET = "present"
-    GET = "get"
-    RESET = "absent"
-    VALID_STATES = (SET, GET, RESET)
-    VALID_VALUE_TYPES = ('int', 'uint', 'bool', 'float', 'double', 'string')
-    previous_value = None
-    is_array = None
-
-    def __init__(self, module):
-        self.module = module
-        self.channel = module.params['channel']
-        self.property = module.params['property']
-        self.value_type = module.params['value_type']
-        self.value = module.params['value']
-        self.force_array = module.params['force_array']
-
-        self.cmd = "{0} --channel {1} --property {2}".format(
-            module.get_bin_path('xfconf-query', True),
-            shlex_quote(self.channel),
-            shlex_quote(self.property)
-        )
-        self.method_map = dict(zip((self.SET, self.GET, self.RESET),
-                                   (self.set, self.get, self.reset)))
-
-        self.does_not = 'Property "{0}" does not exist on channel "{1}".'.format(self.property, self.channel)
-
-        def run(cmd):
-            return module.run_command(cmd, check_rc=False)
-        self._run = run
-
-    def _execute_xfconf_query(self, args=None):
-        try:
-            cmd = self.cmd
-            if args:
-                cmd = "{0} {1}".format(cmd, args)
-
-            self.module.debug("Running cmd={0}".format(cmd))
-            rc, out, err = self._run(cmd)
-            if err.rstrip() == self.does_not:
-                return None
-            if rc or len(err):
-                raise XFConfException('xfconf-query failed with error (rc={0}): {1}'.format(rc, err))
-
-            return out.rstrip()
-
-        except OSError as exception:
-            XFConfException('xfconf-query failed with exception: {0}'.format(exception))
-
-    def get(self):
-        previous_value = self._execute_xfconf_query()
-        if previous_value is None:
-            return
-
-        if "Value is an array with" in previous_value:
-            previous_value = previous_value.split("\n")
-            previous_value.pop(0)
-            previous_value.pop(0)
-
-        return previous_value
-
-    def reset(self):
-        self._execute_xfconf_query("--reset")
-        return None
-
-    @staticmethod
-    def _fix_bool(value):
-        if value.lower() in ("true", "false"):
-            value = value.lower()
-        return value
-
-    def _make_value_args(self, value, value_type):
-        if value_type == 'bool':
-            value = self._fix_bool(value)
-        return " --type '{1}' --set '{0}'".format(shlex_quote(value), shlex_quote(value_type))
-
-    def set(self):
-        args = "--create"
-        if self.is_array:
-            args += " --force-array"
-            for v in zip(self.value, self.value_type):
-                args += self._make_value_args(*v)
-        else:
-            args += self._make_value_args(self.value, self.value_type)
-        self._execute_xfconf_query(args)
-        return self.value
-
-    def call(self, state):
-        return self.method_map[state]()
-
-    def sanitize(self):
-        self.previous_value = self.get()
-
-        if self.value is None and self.value_type is None:
-            return
-        if (self.value is None) ^ (self.value_type is None):
-            raise XFConfException('Must set both "value" and "value_type"')
-
-        # stringify all values - in the CLI they will all be happy strings anyway
-        # and by doing this here the rest of the code can be agnostic to it
-        self.value = [str(v) for v in self.value]
-
-        values_len = len(self.value)
-        types_len = len(self.value_type)
-
-        if types_len == 1:
-            # use one single type for the entire list
-            self.value_type = self.value_type * values_len
-        elif types_len != values_len:
-            # or complain if lists' lengths are different
-            raise XFConfException('Same number of "value" and "value_type" needed')
-
-        # fix boolean values
-        self.value = [self._fix_bool(v[0]) if v[1] == 'bool' else v[0] for v in zip(self.value, self.value_type)]
-
-        # calculates if it is an array
-        self.is_array = self.force_array or isinstance(self.previous_value, list) or values_len > 1
-        if not self.is_array:
-            self.value = self.value[0]
-            self.value_type = self.value_type[0]
-
-
-def main():
-    facts_name = "xfconf"
-    # Setup the Ansible module
-    module = AnsibleModule(
+class XFConfProperty(CmdMixin, StateMixin, ModuleHelper):
+    module = dict(
         argument_spec=dict(
-            state=dict(default=XFConfProperty.SET,
-                       choices=XFConfProperty.VALID_STATES,
+            state=dict(default="present",
+                       choices=("present", "get", "absent"),
                        type='str'),
             channel=dict(required=True, type='str'),
             property=dict(required=True, type='str'),
             value_type=dict(required=False, type='list',
-                            elements='str', choices=XFConfProperty.VALID_VALUE_TYPES),
+                            elements='str', choices=('int', 'uint', 'bool', 'float', 'double', 'string')),
             value=dict(required=False, type='list', elements='raw'),
             force_array=dict(default=False, type='bool', aliases=['array']),
         ),
-        required_if=[
-            ('state', XFConfProperty.SET, ['value', 'value_type'])
-        ],
-        supports_check_mode=True
+        required_if=[('state', 'present', ['value', 'value_type'])],
+        required_together=[('value', 'value_type')],
+        supports_check_mode=True,
     )
 
-    # Force language to 'C' to ensure return values are always formatted in english, even in non-english environments
-    module.run_command_environ_update = dict(LANGUAGE='C')
+    facts_name = "xfconf"
+    default_state = 'present'
+    command = 'xfconf-query'
+    command_args_formats = dict(
+        channel=dict(fmt=('--channel', '{0}'),),
+        property=dict(fmt=('--property', '{0}'),),
+        is_array=dict(fmt="--force-array", style=ArgFormat.BOOLEAN),
+        reset=dict(fmt="--reset", style=ArgFormat.BOOLEAN),
+        create=dict(fmt="--create", style=ArgFormat.BOOLEAN),
+        values_and_types=dict(fmt=values_fmt)
+    )
 
-    state = module.params['state']
+    def update_xfconf_output(self, **kwargs):
+        self.update_output(**kwargs)
+        self.update_facts(**kwargs)
 
-    try:
-        xfconf = XFConfProperty(module)
-        xfconf.sanitize()
+    def __init_module__(self):
+        self.does_not = 'Property "{0}" does not exist on channel "{1}".'.format(self.module.params['property'],
+                                                                                 self.module.params['channel'])
+        self.vars.previous_value = self._get()
 
-        previous_value = xfconf.previous_value
-        facts = {
-            facts_name: dict(
-                channel=xfconf.channel,
-                property=xfconf.property,
-                value_type=xfconf.value_type,
-                value=previous_value,
-            )
-        }
+    def process_command_output(self, rc, out, err):
+        if err.rstrip() == self.does_not:
+            return None
+        if rc or len(err):
+            raise XFConfException('xfconf-query failed with error (rc={0}): {1}'.format(rc, err))
 
-        if state == XFConfProperty.GET \
-                or (previous_value is not None
-                    and (state, set(previous_value)) == (XFConfProperty.SET, set(xfconf.value))):
-            module.exit_json(changed=False, ansible_facts=facts)
-            return
+        result = out.rstrip()
+        if "Value is an array with" in result:
+            result = result.split("\n")
+            result.pop(0)
+            result.pop(0)
 
-        # If check mode, we know a change would have occurred.
-        if module.check_mode:
-            new_value = xfconf.value
+        return result
+
+    @property
+    def changed(self):
+        if self.vars.previous_value is None:
+            return self.vars.value is not None
+        elif self.vars.value is None:
+            return self.vars.previous_value is not None
         else:
-            new_value = xfconf.call(state)
+            return set(self.vars.previous_value) != set(self.vars.value)
 
-        facts[facts_name].update(value=new_value, previous_value=previous_value)
-        module.exit_json(changed=True, ansible_facts=facts)
+    def _get(self):
+        return self.run_command(params=('channel', 'property'))
 
-    except Exception as e:
-        module.fail_json(msg="Failed with exception: {0}".format(e), exception=traceback.format_exc())
+    def state_get(self):
+        self.vars.value = self.vars.previous_value
+
+    def state_absent(self):
+        self.vars.value = None
+        self.run_command(params=('channel', 'property', 'reset'), extra_params={"reset": True})
+
+    def state_present(self):
+        # stringify all values - in the CLI they will all be happy strings anyway
+        # and by doing this here the rest of the code can be agnostic to it
+        self.vars.value = [str(v) for v in self.module.params['value']]
+        value_type = self.module.params['value_type']
+
+        values_len = len(self.vars.value)
+        types_len = len(value_type)
+
+        if types_len == 1:
+            # use one single type for the entire list
+            value_type = value_type * values_len
+        elif types_len != values_len:
+            # or complain if lists' lengths are different
+            raise XFConfException('Number of elements in "value" and "value_type" must be the same')
+
+        # fix boolean values
+        self.vars.value = [fix_bool(v[0]) if v[1] == 'bool' else v[0] for v in zip(self.vars.value, value_type)]
+
+        # calculates if it is an array
+        self.vars.is_array = \
+            bool(self.module.params['force_array']) or \
+            isinstance(self.vars.previous_value, list) or \
+            values_len > 1
+
+        params = ['channel', 'property', 'create']
+        if self.vars.is_array:
+            params.append('is_array')
+        params.append('values_and_types')
+
+        extra_params = dict(values_and_types=(self.vars.value, value_type))
+        extra_params['create'] = True
+        extra_params['is_array'] = self.vars.is_array
+
+        if not self.module.check_mode:
+            self.run_command(params=params, extra_params=extra_params)
+
+        if not self.vars.is_array:
+            self.vars.value = self.vars.value[0]
+
+
+def main():
+    xfconf = XFConfProperty()
+    xfconf.run()
 
 
 if __name__ == '__main__':

tests/unit/plugins/module_utils/test_module_helper.py

@@ -0,0 +1,84 @@
+# -*- coding: utf-8 -*-
+# (c) 2020, Alexei Znamensky <russoz@gmail.com>
+# Copyright (c) 2020 Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+import pytest
+
+from ansible_collections.community.general.plugins.module_utils.module_helper import (
+    ArgFormat, DependencyCtxMgr, ModuleHelper
+)
+
+
+def single_lambda_2star(x, y, z):
+    return ["piggies=[{0},{1},{2}]".format(x, y, z)]
+
+
+ARG_FORMATS = dict(
+    simple_boolean_true=("--superflag", ArgFormat.BOOLEAN, 0, True, ["--superflag"]),
+    simple_boolean_false=("--superflag", ArgFormat.BOOLEAN, 0, False, []),
+    single_printf=("--param=%s", ArgFormat.PRINTF, 0, "potatoes", ["--param=potatoes"]),
+    single_printf_no_substitution=("--param", ArgFormat.PRINTF, 0, "potatoes", ["--param"]),
+    multiple_printf=(["--param", "free-%s"], ArgFormat.PRINTF, 0, "potatoes", ["--param", "free-potatoes"]),
+    single_format=("--param={0}", ArgFormat.FORMAT, 0, "potatoes", ["--param=potatoes"]),
+    single_format_no_substitution=("--param", ArgFormat.FORMAT, 0, "potatoes", ["--param"]),
+    multiple_format=(["--param", "free-{0}"], ArgFormat.FORMAT, 0, "potatoes", ["--param", "free-potatoes"]),
+    single_lambda_0star=((lambda v: ["piggies=[{0},{1},{2}]".format(v[0], v[1], v[2])]),
+                         None, 0, ['a', 'b', 'c'], ["piggies=[a,b,c]"]),
+    single_lambda_1star=((lambda a, b, c: ["piggies=[{0},{1},{2}]".format(a, b, c)]),
+                         None, 1, ['a', 'b', 'c'], ["piggies=[a,b,c]"]),
+    single_lambda_2star=(single_lambda_2star, None, 2, dict(z='c', x='a', y='b'), ["piggies=[a,b,c]"])
+)
+ARG_FORMATS_IDS = sorted(ARG_FORMATS.keys())
+
+
+@pytest.mark.parametrize('fmt, style, stars, value, expected',
+                         (ARG_FORMATS[tc] for tc in ARG_FORMATS_IDS),
+                         ids=ARG_FORMATS_IDS)
+def test_arg_format(fmt, style, stars, value, expected):
+    af = ArgFormat('name', fmt, style, stars)
+    actual = af.to_text(value)
+    print("formatted string = {0}".format(actual))
+    assert actual == expected
+
+
+ARG_FORMATS_FAIL = dict(
+    int_fmt=(3, None, 0, "", [""]),
+    bool_fmt=(True, None, 0, "", [""]),
+)
+ARG_FORMATS_FAIL_IDS = sorted(ARG_FORMATS_FAIL.keys())
+
+
+@pytest.mark.parametrize('fmt, style, stars, value, expected',
+                         (ARG_FORMATS_FAIL[tc] for tc in ARG_FORMATS_FAIL_IDS),
+                         ids=ARG_FORMATS_FAIL_IDS)
+def test_arg_format_fail(fmt, style, stars, value, expected):
+    with pytest.raises(TypeError):
+        af = ArgFormat('name', fmt, style, stars)
+        actual = af.to_text(value)
+        print("formatted string = {0}".format(actual))
+
+
+def test_dependency_ctxmgr():
+    ctx = DependencyCtxMgr("POTATOES", "Potatoes must be installed")
+    with ctx:
+        import potatoes_that_will_never_be_there
+    print("POTATOES: ctx.text={0}".format(ctx.text))
+    assert ctx.text == "Potatoes must be installed"
+    assert not ctx.has_it
+
+    ctx = DependencyCtxMgr("POTATOES2")
+    with ctx:
+        import potatoes_that_will_never_be_there_again
+    assert not ctx.has_it
+    print("POTATOES2: ctx.text={0}".format(ctx.text))
+    assert ctx.text.startswith("No module named")
+    assert "potatoes_that_will_never_be_there_again" in ctx.text
+
+    ctx = DependencyCtxMgr("TYPING")
+    with ctx:
+        import sys
+    assert ctx.has_it

tests/unit/plugins/modules/system/test_xfconf.py

@@ -9,7 +9,6 @@ __metaclass__ = type
 
 import json
 
-from ansible.module_utils import basic
 from ansible_collections.community.general.plugins.modules.system import xfconf
 
 import pytest
@@ -22,7 +21,7 @@ def patch_xfconf(mocker):
     """
     Function used for mocking some parts of redhat_subscribtion module
     """
-    mocker.patch('ansible_collections.community.general.plugins.modules.system.xfconf.AnsibleModule.get_bin_path',
+    mocker.patch('ansible_collections.community.general.plugins.module_utils.module_helper.AnsibleModule.get_bin_path',
                  return_value='/testbin/xfconf-query')
 
 
@@ -41,7 +40,6 @@ def test_without_required_parameters(capfd, patch_xfconf):
 
 
 TEST_CASES = [
-    # Test the case, when the system is already registered
     [
         {'channel': 'xfwm4', 'property': '/general/inactive_opacity', 'state': 'get'},
         {
@@ -49,15 +47,35 @@ TEST_CASES = [
             'run_command.calls': [
                 (
                     # Calling of following command will be asserted
-                    '/testbin/xfconf-query --channel xfwm4 --property /general/inactive_opacity',
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/inactive_opacity'],
                     # Was return code checked?
-                    {'check_rc': False},
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
                     # Mock of returned code, stdout and stderr
-                    (0, '100/n', '',),
+                    (0, '100\n', '',),
                 ),
             ],
             'changed': False,
-            'value': '100'
+            'previous_value': '100',
+            'value': '100',
+        }
+    ],
+    [
+        {'channel': 'xfwm4', 'property': '/general/i_dont_exist', 'state': 'get'},
+        {
+            'id': 'test_simple_property_get_nonexistent',
+            'run_command.calls': [
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/i_dont_exist'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (1, '', 'Property "/general/i_dont_exist" does not exist on channel "xfwm4".\n',),
+                ),
+            ],
+            'changed': False,
+            'previous_value': None,
+            'value': None,
         }
     ],
     [
@@ -67,15 +85,16 @@ TEST_CASES = [
             'run_command.calls': [
                 (
                     # Calling of following command will be asserted
-                    '/testbin/xfconf-query --channel xfwm4 --property /general/workspace_names',
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names'],
                     # Was return code checked?
-                    {'check_rc': False},
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
                     # Mock of returned code, stdout and stderr
                     (0, 'Value is an array with 3 items:\n\nMain\nWork\nTmp\n', '',),
                 ),
             ],
             'changed': False,
-            'value': ['Main', 'Work', 'Tmp']
+            'previous_value': ['Main', 'Work', 'Tmp'],
+            'value': ['Main', 'Work', 'Tmp'],
         },
     ],
     [
@@ -85,15 +104,16 @@ TEST_CASES = [
             'run_command.calls': [
                 (
                     # Calling of following command will be asserted
-                    '/testbin/xfconf-query --channel xfwm4 --property /general/use_compositing',
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/use_compositing'],
                     # Was return code checked?
-                    {'check_rc': False},
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
                     # Mock of returned code, stdout and stderr
                     (0, 'true', '',),
                 ),
             ],
             'changed': False,
-            'value': True
+            'previous_value': 'true',
+            'value': 'true',
         },
     ],
     [
@@ -103,15 +123,84 @@ TEST_CASES = [
             'run_command.calls': [
                 (
                     # Calling of following command will be asserted
-                    '/testbin/xfconf-query --channel xfwm4 --property /general/use_compositing',
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/use_compositing'],
                     # Was return code checked?
-                    {'check_rc': False},
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
                     # Mock of returned code, stdout and stderr
                     (0, 'false', '',),
                 ),
             ],
             'changed': False,
-            'value': False
+            'previous_value': 'false',
+            'value': 'false',
+        },
+    ],
+    [
+        {
+            'channel': 'xfwm4',
+            'property': '/general/inactive_opacity',
+            'state': 'present',
+            'value_type': 'int',
+            'value': 90,
+        },
+        {
+            'id': 'test_property_set_property',
+            'run_command.calls': [
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/inactive_opacity'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, '100\n', '',),
+                ),
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/inactive_opacity',
+                     '--create', '--type', 'int', '--set', '90'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, '', '',),
+                ),
+            ],
+            'changed': True,
+            'previous_value': '100',
+            'value': '90',
+        },
+    ],
+    [
+        {
+            'channel': 'xfwm4',
+            'property': '/general/inactive_opacity',
+            'state': 'present',
+            'value_type': 'int',
+            'value': 90,
+        },
+        {
+            'id': 'test_property_set_property_same_value',
+            'run_command.calls': [
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/inactive_opacity'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, '90\n', '',),
+                ),
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/inactive_opacity',
+                     '--create', '--type', 'int', '--set', '90'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, '', '',),
+                ),
+            ],
+            'changed': False,
+            'previous_value': '90',
+            'value': '90',
         },
     ],
     [
@@ -127,18 +216,19 @@ TEST_CASES = [
             'run_command.calls': [
                 (
                     # Calling of following command will be asserted
-                    '/testbin/xfconf-query --channel xfwm4 --property /general/workspace_names',
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names'],
                     # Was return code checked?
-                    {'check_rc': False},
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
                     # Mock of returned code, stdout and stderr
                     (0, 'Value is an array with 3 items:\n\nMain\nWork\nTmp\n', '',),
                 ),
                 (
                     # Calling of following command will be asserted
-                    "/testbin/xfconf-query --channel xfwm4 --property /general/workspace_names --create "
-                    "--force-array --type 'string' --set 'A' --type 'string' --set 'B' --type 'string' --set 'C'",
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names',
+                     '--create', '--force-array', '--type', 'string', '--set', 'A', '--type', 'string', '--set', 'B',
+                     '--type', 'string', '--set', 'C'],
                     # Was return code checked?
-                    {'check_rc': False},
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
                     # Mock of returned code, stdout and stderr
                     (0, '', '',),
                 ),
@@ -148,6 +238,73 @@ TEST_CASES = [
             'value': ['A', 'B', 'C'],
         },
     ],
+    [
+        {
+            'channel': 'xfwm4',
+            'property': '/general/workspace_names',
+            'state': 'present',
+            'value_type': 'string',
+            'value': ['A', 'B', 'C'],
+        },
+        {
+            'id': 'test_property_set_array_to_same_value',
+            'run_command.calls': [
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, 'Value is an array with 3 items:\n\nA\nB\nC\n', '',),
+                ),
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names',
+                     '--create', '--force-array', '--type', 'string', '--set', 'A', '--type', 'string', '--set', 'B',
+                     '--type', 'string', '--set', 'C'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, '', '',),
+                ),
+            ],
+            'changed': False,
+            'previous_value': ['A', 'B', 'C'],
+            'value': ['A', 'B', 'C'],
+        },
+    ],
+    [
+        {
+            'channel': 'xfwm4',
+            'property': '/general/workspace_names',
+            'state': 'absent',
+        },
+        {
+            'id': 'test_property_reset_value',
+            'run_command.calls': [
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, 'Value is an array with 3 items:\n\nA\nB\nC\n', '',),
+                ),
+                (
+                    # Calling of following command will be asserted
+                    ['/testbin/xfconf-query', '--channel', 'xfwm4', '--property', '/general/workspace_names',
+                     '--reset'],
+                    # Was return code checked?
+                    {'environ_update': {'LANGUAGE': 'C'}, 'check_rc': False},
+                    # Mock of returned code, stdout and stderr
+                    (0, '', '',),
+                ),
+            ],
+            'changed': True,
+            'previous_value': ['A', 'B', 'C'],
+            'value': None,
+        },
+    ],
 ]
 TEST_CASES_IDS = [item[1]['id'] for item in TEST_CASES]
 
@@ -165,7 +322,7 @@ def test_xfconf(mocker, capfd, patch_xfconf, testcase):
     # Mock function used for running commands first
     call_results = [item[2] for item in testcase['run_command.calls']]
     mock_run_command = mocker.patch(
-        'ansible_collections.community.general.plugins.modules.system.xfconf.AnsibleModule.run_command',
+        'ansible_collections.community.general.plugins.module_utils.module_helper.AnsibleModule.run_command',
         side_effect=call_results)
 
     # Try to run test case
@@ -174,7 +331,8 @@ def test_xfconf(mocker, capfd, patch_xfconf, testcase):
 
     out, err = capfd.readouterr()
     results = json.loads(out)
-    print("results = %s" % results)
+    print("testcase =\n%s" % testcase)
+    print("results =\n%s" % results)
     assert 'changed' in results
     assert results['changed'] == testcase['changed']
     if 'msg' in results: