avocado.plugins.multiplex: Make --multiplex optional

The `--multiplex` is about to be changed into a separate plugin. It does
not sound fair to keep it as default positional argument of the
`multiplex` command. Let's sync the naming scheme and require
`--multiplex` for it.

This also means the `-m` is optional so one can run `avocado multiplex`
without arguments to get default multiplex values.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/plugins/multiplex.py

@@ -35,12 +35,10 @@ class Multiplex(CLICmd):
         super(Multiplex, self).__init__(*args, **kwargs)
 
     def configure(self, parser):
-        if multiplexer.MULTIPLEX_CAPABLE is False:
-            return
-
         parser = super(Multiplex, self).configure(parser)
-        parser.add_argument('multiplex', nargs='+',
-                            help='Path(s) to a multiplex file(s)')
+        if multiplexer.MULTIPLEX_CAPABLE:
+            parser.add_argument("-m", '--multiplex', nargs='*',
+                                help='Path(s) to a multiplex file(s)')
 
         parser.add_argument('--filter-only', nargs='*', default=[],
                             help='Filter only path(s) from multiplexing')

docs/source/MultiplexConfig.rst

@@ -59,7 +59,7 @@ is disabled, so the value of node name is always as written in the yaml
 file (unlike values, where `yes` converts to `True` and such).
 
 Nodes are organized in parent-child relationship and together they create
-a tree. To view this structure use ``avocado multiplex --tree <file>``::
+a tree. To view this structure use ``avocado multiplex --tree -m <file>``::
 
  ┗━━ run
       ┣━━ hw
@@ -422,7 +422,7 @@ Let's take a second look at the first example::
 After filters are applied (simply removes non-matching variants), leaves
 are gathered and all variants are generated::
 
-    $ avocado multiplex examples/mux-environment.yaml
+    $ avocado multiplex -m examples/mux-environment.yaml
     Variants generated:
     Variant 1:    /hw/cpu/intel, /hw/disk/scsi, /distro/fedora, /env/debug
     Variant 2:    /hw/cpu/intel, /hw/disk/scsi, /distro/fedora, /env/prod

docs/source/WritingTests.rst

@@ -174,9 +174,9 @@ it's injected directly into the specified path and it's up to the test/framework
 developer to get the value from this location (using path or adding the path to
 ``mux-path``). To understand the difference execute those commands::
 
-    $ avocado multiplex -t examples/tests/sleeptest.py.data/sleeptest.yaml
-    $ avocado multiplex -t duration:examples/tests/sleeptest.py.data/sleeptest.yaml
-    $ avocado multiplex -t /my/location:examples/tests/sleeptest.py.data/sleeptest.yaml
+    $ avocado multiplex -t -m examples/tests/sleeptest.py.data/sleeptest.yaml
+    $ avocado multiplex -t -m duration:examples/tests/sleeptest.py.data/sleeptest.yaml
+    $ avocado multiplex -t -m /my/location:examples/tests/sleeptest.py.data/sleeptest.yaml
 
 Note that, as your multiplex file specifies all parameters for sleeptest, you
 can't leave the test ID empty::

selftests/functional/test_multiplex.py

@@ -43,18 +43,18 @@ class MultiplexTests(unittest.TestCase):
         return result
 
     def test_mplex_plugin(self):
-        cmd_line = './scripts/avocado multiplex examples/tests/sleeptest.py.data/sleeptest.yaml'
+        cmd_line = './scripts/avocado multiplex -m examples/tests/sleeptest.py.data/sleeptest.yaml'
         expected_rc = exit_codes.AVOCADO_ALL_OK
         self.run_and_check(cmd_line, expected_rc)
 
     def test_mplex_plugin_nonexistent(self):
-        cmd_line = './scripts/avocado multiplex nonexist'
+        cmd_line = './scripts/avocado multiplex -m nonexist'
         expected_rc = exit_codes.AVOCADO_JOB_FAIL
         result = self.run_and_check(cmd_line, expected_rc)
         self.assertIn('No such file or directory', result.stderr)
 
     def test_mplex_debug(self):
-        cmd_line = ('./scripts/avocado multiplex -c -d '
+        cmd_line = ('./scripts/avocado multiplex -c -d -m '
                     '/:examples/mux-selftest.yaml '
                     '/:examples/mux-environment.yaml '
                     '/:examples/mux-selftest.yaml '