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.py

@@ -23,16 +23,14 @@ __metaclass__ = type
 import sys
 import json
 import syslog
-from io import BytesIO, StringIO
-
-from ansible.compat.six import PY3
-from ansible.utils.unicode import to_bytes
 
 from ansible.compat.tests import unittest
 from ansible.compat.tests.mock import patch, MagicMock
+from units.mock.procenv import swap_stdin_and_argv
 
 from ansible.module_utils import basic
 
+
 try:
     # Python 3.4+
     from importlib import reload
@@ -44,15 +42,12 @@ except ImportError:
 
 
 class TestAnsibleModuleSysLogSmokeTest(unittest.TestCase):
-
     def setUp(self):
         args = json.dumps(dict(ANSIBLE_MODULE_ARGS={}, ANSIBLE_MODULE_CONSTANTS={}))
-        self.real_stdin = sys.stdin
-        if PY3:
-            sys.stdin = StringIO(args)
-            sys.stdin.buffer = BytesIO(to_bytes(args))
-        else:
-            sys.stdin = BytesIO(to_bytes(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__()
 
         self.am = basic.AnsibleModule(
             argument_spec = dict(),
@@ -64,7 +59,8 @@ class TestAnsibleModuleSysLogSmokeTest(unittest.TestCase):
             basic.has_journal = False
 
     def tearDown(self):
-        sys.stdin = self.real_stdin
+        # 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)
         basic.has_journal = self.has_journal
 
     def test_smoketest_syslog(self):
@@ -84,20 +80,18 @@ class TestAnsibleModuleJournaldSmokeTest(unittest.TestCase):
 
     def setUp(self):
         args = json.dumps(dict(ANSIBLE_MODULE_ARGS={}, ANSIBLE_MODULE_CONSTANTS={}))
-        self.real_stdin = sys.stdin
-        if PY3:
-            sys.stdin = StringIO(args)
-            sys.stdin.buffer = BytesIO(to_bytes(args))
-        else:
-            sys.stdin = BytesIO(to_bytes(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__()
 
         self.am = basic.AnsibleModule(
             argument_spec = dict(),
         )
 
     def tearDown(self):
-        sys.stdin = self.real_stdin
+        # 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)
 
     @unittest.skipUnless(basic.has_journal, 'python systemd bindings not installed')
     def test_smoketest_journal(self):
@@ -134,26 +128,26 @@ class TestAnsibleModuleLogSyslog(unittest.TestCase):
 
     def setUp(self):
         args = json.dumps(dict(ANSIBLE_MODULE_ARGS={}, ANSIBLE_MODULE_CONSTANTS={}))
-        self.real_stdin = sys.stdin
-        if PY3:
-            sys.stdin = StringIO(args)
-            sys.stdin.buffer = BytesIO(to_bytes(args))
-        else:
-            sys.stdin = BytesIO(to_bytes(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__()
 
         self.am = basic.AnsibleModule(
             argument_spec = dict(),
         )
+
         self.has_journal = basic.has_journal
         if self.has_journal:
             # Systems with journal can still test syslog
             basic.has_journal = False
 
     def tearDown(self):
-        sys.stdin = self.real_stdin
+        # teardown/reset
         basic.has_journal = self.has_journal
 
+        # 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)
+
     @patch('syslog.syslog', autospec=True)
     def test_no_log(self, mock_func):
         no_log = self.am.no_log
@@ -191,21 +185,22 @@ class TestAnsibleModuleLogJournal(unittest.TestCase):
             b'non-utf8 :\xff: test': b'non-utf8 :\xff: test'.decode('utf-8', 'replace')
             }
 
+    # overriding run lets us use context managers for setup/teardown-esque behavior
     def setUp(self):
         args = json.dumps(dict(ANSIBLE_MODULE_ARGS={}, ANSIBLE_MODULE_CONSTANTS={}))
-        self.real_stdin = sys.stdin
-        if PY3:
-            sys.stdin = StringIO(args)
-            sys.stdin.buffer = BytesIO(to_bytes(args))
-        else:
-            sys.stdin = BytesIO(to_bytes(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__()
 
         self.am = basic.AnsibleModule(
             argument_spec = dict(),
         )
 
         self.has_journal = basic.has_journal
-        basic.has_journal = True
+        if self.has_journal:
+            # Systems with journal can still test syslog
+            basic.has_journal = False
+
         self.module_patcher = None
 
         # In case systemd-python is not installed
@@ -218,9 +213,12 @@ class TestAnsibleModuleLogJournal(unittest.TestCase):
                 self._fake_out_reload(basic)
 
     def tearDown(self):
-        sys.stdin = self.real_stdin
+        # 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)
 
+        # teardown/reset
         basic.has_journal = self.has_journal
+
         if self.module_patcher:
             self.module_patcher.stop()
             reload(basic)