Runner plugins: standardize option group names, metavars and others

This is a collection of little small touches that, IMHO, add a little
bit more consistency to the plugins involved in the Avocado `run`
command.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado/core/plugins/htmlresult.py

@@ -279,8 +279,8 @@ class HTML(plugin.Plugin):
         self.parser = parser
         self.parser.runner.output.add_argument(
             '--html', type=str,
-            dest='html_output',
-            help=('Enable HTML output to the file where the result should be '
+            dest='html_output', metavar='FILE',
+            help=('Enable HTML output to the FILE where the result should be '
                   'written. The value - (output to stdout) is not supported '
                   'since not all HTML resources can be embedded into a '
                   'single file (page resources will be copied to the '

avocado/core/plugins/jsonresult.py

@@ -104,8 +104,8 @@ class JSON(plugin.Plugin):
         self.parser = parser
         self.parser.runner.output.add_argument(
             '--json', type=str,
-            dest='json_output',
-            help='Enable JSON output to the file where the result should be written. '
+            dest='json_output', metavar='FILE',
+            help='Enable JSON result format and write it to FILE. '
                  "Use '-' to redirect to the standard output.")
         self.configured = True
 

avocado/core/plugins/remote.py

@@ -37,7 +37,7 @@ class RunRemote(plugin.Plugin):
             self.enabled = False
             return
         username = getpass.getuser()
-        msg = 'run on a remote machine arguments'
+        msg = 'test execution on a remote machine'
         self.remote_parser = parser.runner.add_argument_group(msg)
         self.remote_parser.add_argument('--remote-hostname',
                                         dest='remote_hostname', default=None,

avocado/core/plugins/runner.py

@@ -82,7 +82,7 @@ class TestRunner(plugin.Plugin):
                                        '(hardware details, profilers, etc.). '
                                        'Current:  %(default)s'))
 
-        self.parser.output = self.parser.add_argument_group('output related arguments')
+        self.parser.output = self.parser.add_argument_group('output and result format')
 
         self.parser.output.add_argument(
             '-s', '--silent', action='store_true', default=False,
@@ -116,10 +116,11 @@ class TestRunner(plugin.Plugin):
                                      'Current: on (output check enabled)'))
 
         if multiplexer.MULTIPLEX_CAPABLE:
-            mux = self.parser.add_argument_group('multiplex arguments')
-            mux.add_argument('-m', '--multiplex-files', nargs='*', default=None,
-                             help='Path(s) to a avocado multiplex (.yaml) '
-                             'file(s) (order dependent)')
+            mux = self.parser.add_argument_group('multiplexer use on test execution')
+            mux.add_argument('-m', '--multiplex-files', nargs='*',
+                             default=None, metavar='FILE',
+                             help='Location of one or more Avocado multiplex (.yaml) '
+                             'FILE(s) (order dependent)')
             mux.add_argument('--filter-only', nargs='*', default=[],
                              help='Filter only path(s) from multiplexing')
             mux.add_argument('--filter-out', nargs='*', default=[],

avocado/core/plugins/vm.py

@@ -38,9 +38,8 @@ class RunVM(plugin.Plugin):
             return
         username = getpass.getuser()
         default_hypervisor_uri = 'qemu:///system'
-        self.vm_parser = parser.runner.add_argument_group('run on a libvirt '
-                                                          'domain arguments')
-
+        msg = 'test execution on a Virtual Machine'
+        self.vm_parser = parser.runner.add_argument_group(msg)
         self.vm_parser.add_argument('--vm-domain', dest='vm_domain',
                                     help=('Specify Libvirt Domain Name'))
         self.vm_parser.add_argument('--vm-hypervisor-uri',

avocado/core/plugins/wrapper.py

@@ -33,7 +33,7 @@ class Wrapper(plugin.Plugin):
     def configure(self, parser):
         self.parser = parser
         wrap_group = self.parser.runner.add_argument_group(
-            'Wrapper support')
+            'wrapper support')
         wrap_group.add_argument('--wrapper', action='append', default=[],
                                 metavar='SCRIPT[:EXECUTABLE]',
                                 help='Use a script to wrap executables run by '

avocado/core/plugins/xunit.py

@@ -228,8 +228,8 @@ class XUnit(plugin.Plugin):
     def configure(self, parser):
         self.parser = parser
         self.parser.runner.output.add_argument(
-            '--xunit', type=str, dest='xunit_output',
-            help=('Enable xUnit output to the file where the result should be written. '
+            '--xunit', type=str, dest='xunit_output', metavar='FILE',
+            help=('Enable xUnit result format and write it to FILE. '
                   "Use '-' to redirect to the standard output."))
         self.configured = True