Porting tests to pytest (#33387)

* Porting tests to pytest

* Achievement Get: No longer need mock/generator.py
  * Now done via pytest's parametrization
  * Port safe_eval to pytest
  * Port text tests to pytest
  * Port test_set_mode_if_different to pytest

* Change conftest AnsibleModule fixtures to be more flexible
  * Move the AnsibleModules fixtures to module_utils/conftest.py for sharing
  * Testing the argspec code requires:
    * injecting both the argspec and the arguments.
    * Patching the arguments into sys.stdin at a different level

* More porting to obsolete mock/procenv.py
  * Port run_command to pytest
  * Port known_hosts tests to pytest
  * Port safe_eval to pytest
  * Port test_distribution_version.py to pytest
  * Port test_log to pytest
  * Port test__log_invocation to pytest
  * Remove unneeded import of procenv in test_postgresql

* Port test_pip to pytest style
  * As part of this, create a pytest ansiblemodule fixture in
    modules/conftest.py.  This is slightly different than the
    approach taken in module_utils because here we need to override the
    AnsibleModule that the modules will inherit from instead of one that
    we're instantiating ourselves.

* Fixup usage of parametrization in test_deprecate_warn

* Check that the pip module failed in our test

test/units/mock/generator.py

@@ -1,72 +0,0 @@
-# Copyright 2016 Toshio Kuratomi <tkuratomi@ansible.com>
-#
-# This file is part of Ansible
-#
-# Ansible is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# Ansible is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
-
-# Make coding more python3-ish
-from __future__ import (absolute_import, division, print_function)
-__metaclass__ = type
-
-from collections import Mapping
-
-
-def make_method(func, args, kwargs):
-
-    def test_method(self):
-        func(self, *args, **kwargs)
-
-    # Format the argument string
-    arg_string = ', '.join(repr(a) for a in args)
-    kwarg_string = ', '.join('{0}={1}'.format(item[0], repr(item[1])) for item in kwargs.items())
-    arg_list = []
-    if arg_string:
-        arg_list.append(arg_string)
-    if kwarg_string:
-        arg_list.append(kwarg_string)
-
-    test_method.__name__ = 'test_{0}({1})'.format(func.__name__, ', '.join(arg_list))
-    return test_method
-
-
-def add_method(func, *combined_args):
-    """
-    Add a test case via a class decorator.
-
-    nose uses generators for this but doesn't work with unittest.TestCase
-    subclasses.  So we have to write our own.
-
-    The first argument to this decorator is a test function.  All subsequent
-    arguments are the arguments to create each generated test function with in
-    the following format:
-
-    Each set of arguments is a two-tuple.  The first element is an iterable of
-    positional arguments.  the second is a dict representing the kwargs.
-    """
-    def wrapper(cls):
-        for combined_arg in combined_args:
-            if len(combined_arg) == 2:
-                args = combined_arg[0]
-                kwargs = combined_arg[1]
-            elif isinstance(combined_arg[0], Mapping):
-                args = []
-                kwargs = combined_arg[0]
-            else:
-                args = combined_arg[0]
-                kwargs = {}
-            test_method = make_method(func, args, kwargs)
-            setattr(cls, test_method.__name__, test_method)
-        return cls
-
-    return wrapper