add _load_params debug overrides for module args/file passed on cmdline

Updated python module wrapper explode method to drop 'args' file next to module.
Both execute() and excommunicate() debug methods now pass the module args via file to enable debuggers that are picky about stdin.
Updated unit tests to use a context manager for masking/restoring default streams and argv.

test/units/module_utils/basic/test__log_invocation.py

@@ -22,75 +22,62 @@ __metaclass__ = type
 
 import sys
 import json
-from io import BytesIO, StringIO
 
-from ansible.compat.six import PY3
-from ansible.utils.unicode import to_bytes
+from units.mock.procenv import swap_stdin_and_argv
 
 from ansible.compat.tests import unittest
 from ansible.compat.tests.mock import MagicMock
 
+
 class TestModuleUtilsBasic(unittest.TestCase):
-    def setUp(self):
-        self.real_stdin = sys.stdin
-        args = json.dumps(
+    @unittest.skipIf(sys.version_info[0] >= 3, "Python 3 is not supported on targets (yet)")
+    def test_module_utils_basic__log_invocation(self):
+        with swap_stdin_and_argv(stdin_data=json.dumps(
             dict(
                 ANSIBLE_MODULE_ARGS=dict(
                     foo=False, bar=[1,2,3], bam="bam", baz=u'baz'),
                 ANSIBLE_MODULE_CONSTANTS=dict()
+                ))):
+            from ansible.module_utils import basic
+
+            # test basic log invocation
+            am = basic.AnsibleModule(
+                argument_spec=dict(
+                    foo = dict(default=True, type='bool'),
+                    bar = dict(default=[], type='list'),
+                    bam = dict(default="bam"),
+                    baz = dict(default=u"baz"),
+                    password = dict(default=True),
+                    no_log = dict(default="you shouldn't see me", no_log=True),
+                ),
+            )
+
+            am.log = MagicMock()
+            am._log_invocation()
+
+            # Message is generated from a dict so it will be in an unknown order.
+            # have to check this manually rather than with assert_called_with()
+            args = am.log.call_args[0]
+            self.assertEqual(len(args), 1)
+            message = args[0]
+
+            self.assertEqual(len(message), len('Invoked with bam=bam bar=[1, 2, 3] foo=False baz=baz no_log=NOT_LOGGING_PARAMETER password=NOT_LOGGING_PASSWORD'))
+            self.assertTrue(message.startswith('Invoked with '))
+            self.assertIn(' bam=bam', message)
+            self.assertIn(' bar=[1, 2, 3]', message)
+            self.assertIn(' foo=False', message)
+            self.assertIn(' baz=baz', message)
+            self.assertIn(' no_log=NOT_LOGGING_PARAMETER', message)
+            self.assertIn(' password=NOT_LOGGING_PASSWORD', message)
+
+            kwargs = am.log.call_args[1]
+            self.assertEqual(kwargs,
+                    dict(log_args={
+                        'foo': 'False',
+                        'bar': '[1, 2, 3]',
+                        'bam': 'bam',
+                        'baz': 'baz',
+                        'password': 'NOT_LOGGING_PASSWORD',
+                        'no_log': 'NOT_LOGGING_PARAMETER',
+                    })
                 )
-            )
-        if PY3:
-            sys.stdin = StringIO(args)
-            sys.stdin.buffer = BytesIO(to_bytes(args))
-        else:
-            sys.stdin = BytesIO(to_bytes(args))
-
-    def tearDown(self):
-        sys.stdin = self.real_stdin
-
-    @unittest.skipIf(sys.version_info[0] >= 3, "Python 3 is not supported on targets (yet)")
-    def test_module_utils_basic__log_invocation(self):
-        from ansible.module_utils import basic
-
-        # test basic log invocation
-        am = basic.AnsibleModule(
-            argument_spec=dict(
-                foo = dict(default=True, type='bool'),
-                bar = dict(default=[], type='list'),
-                bam = dict(default="bam"),
-                baz = dict(default=u"baz"),
-                password = dict(default=True),
-                no_log = dict(default="you shouldn't see me", no_log=True),
-            ),
-        )
-
-        am.log = MagicMock()
-        am._log_invocation()
-
-        # Message is generated from a dict so it will be in an unknown order.
-        # have to check this manually rather than with assert_called_with()
-        args = am.log.call_args[0]
-        self.assertEqual(len(args), 1)
-        message = args[0]
-
-        self.assertEqual(len(message), len('Invoked with bam=bam bar=[1, 2, 3] foo=False baz=baz no_log=NOT_LOGGING_PARAMETER password=NOT_LOGGING_PASSWORD'))
-        self.assertTrue(message.startswith('Invoked with '))
-        self.assertIn(' bam=bam', message)
-        self.assertIn(' bar=[1, 2, 3]', message)
-        self.assertIn(' foo=False', message)
-        self.assertIn(' baz=baz', message)
-        self.assertIn(' no_log=NOT_LOGGING_PARAMETER', message)
-        self.assertIn(' password=NOT_LOGGING_PASSWORD', message)
-
-        kwargs = am.log.call_args[1]
-        self.assertEqual(kwargs, 
-                dict(log_args={
-                    'foo': 'False',
-                    'bar': '[1, 2, 3]',
-                    'bam': 'bam',
-                    'baz': 'baz',
-                    'password': 'NOT_LOGGING_PASSWORD',
-                    'no_log': 'NOT_LOGGING_PARAMETER',
-                })
-            )