Command module bug fix, tests and cleanup. (#30432)

* Add more command integration tests.
* Remove unnecessary command test debug tasks.
* Fix traceback in command module for empty args.
* Remove unreachable code.

lib/ansible/modules/commands/command.py

@@ -144,7 +144,7 @@ def main():
         module.warn("As of Ansible 2.4, the parameter 'executable' is no longer supported with the 'command' module. Not using '%s'." % executable)
         executable = None
 
-    if args.strip() == '':
+    if not args or args.strip() == '':
         module.fail_json(rc=256, msg="no command given")
 
     if chdir:
@@ -187,11 +187,6 @@ def main():
     endd = datetime.datetime.now()
     delta = endd - startd
 
-    if out is None:
-        out = b''
-    if err is None:
-        err = b''
-
     result = dict(
         cmd=args,
         stdout=out.rstrip(b"\r\n"),