A little unittest refactoring (#16704)

A little unittest refactoring

* Add a class decorator to generate tests when using a unittest.TestCase base class
* Add a TestCase subclass with setUp() and tearDown() that sets up
  module parameter parsing
* Move test_safe_eval to use the class decorator and ModuleTestCase base
  class
* Move testing of set_mode_if_different into its own file and separate
  some test methods out so we get better errors and more coverage in
  case of errors.
* Naming convention for test cases doesn't need to duplicate information
  that's already in the file path.

test/units/mock/generator.py

@@ -0,0 +1,71 @@
+# 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

test/units/mock/procenv.py

@@ -1,4 +1,5 @@
 # (c) 2016, Matt Davis <mdavis@ansible.com>
+# (c) 2016, Toshio Kuratomi <tkuratomi@ansible.com>
 #
 # This file is part of Ansible
 #
@@ -20,10 +21,12 @@ from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
 import sys
+import json
 
 from contextlib import contextmanager
 from io import BytesIO, StringIO
 from ansible.compat.six import PY3
+from ansible.compat.tests import unittest
 from ansible.utils.unicode import to_bytes
 
 @contextmanager
@@ -54,4 +57,19 @@ def swap_stdout():
     fake_stream = BytesIO()
     sys.stdout = fake_stream
     yield fake_stream
-    sys.stdout = old_stdout
+    sys.stdout = old_stdout
+
+class ModuleTestCase(unittest.TestCase):
+    def setUp(self, module_args=None):
+        if module_args is None:
+            module_args = {}
+
+        args = json.dumps(dict(ANSIBLE_MODULE_ARGS=module_args))
+
+        # unittest doesn't have a clean place to use a context manager, so we have to enter/exit manually
+        self.stdin_swap = swap_stdin_and_argv(stdin_data=args)
+        self.stdin_swap.__enter__()
+
+    def tearDown(self):
+        # unittest doesn't have a clean place to use a context manager, so we have to enter/exit manually
+        self.stdin_swap.__exit__(None, None, None)