multiplexer: Graceful disable it if PyYAML is not installed.

Test for feature MULTIPLEX_CAPABLE to graful disable the multiplexer
if PyYAML is not installed.
Signed-off-by: NRudá Moura <rmoura@redhat.com>

avocado/core/tree.py

@@ -37,12 +37,17 @@ import collections
 import os
 import re
 
-import yaml
-
-
 try:
-    from yaml import CLoader as Loader
+    import yaml
 except ImportError:
+    MULTIPLEX_CAPABLE = False
+else:
+    MULTIPLEX_CAPABLE = True
+
+if MULTIPLEX_CAPABLE:
+    try:
+        from yaml import CLoader as Loader
+    except ImportError:
         from yaml import Loader
 
 

avocado/job.py

@@ -90,6 +90,7 @@ class Job(object):
                 self.loglevel = mapping[raw_log_level]
             else:
                 self.loglevel = logging.DEBUG
+            if multiplexer.MULTIPLEX_CAPABLE:
                 self.multiplex_files = args.multiplex_files
             self.show_job_log = args.show_job_log
             self.silent = args.silent
@@ -259,6 +260,7 @@ class Job(object):
 
         params_list = self.test_loader.discover_urls(urls)
 
+        if multiplexer.MULTIPLEX_CAPABLE:
             if multiplex_files is None:
                 if self.args and self.args.multiplex_files is not None:
                     multiplex_files = self.args.multiplex_files

avocado/multiplexer.py

@@ -23,6 +23,8 @@ import itertools
 
 from avocado.core import tree
 
+MULTIPLEX_CAPABLE = tree.MULTIPLEX_CAPABLE
+
 
 def tree2pools(node, mux=True):
     """

avocado/plugins/multiplexer.py

@@ -32,6 +32,9 @@ class Multiplexer(plugin.Plugin):
     enabled = True
 
     def configure(self, parser):
+        if multiplexer.MULTIPLEX_CAPABLE is False:
+            self.enabled = False
+            return
         self.parser = parser.subcommands.add_parser(
             'multiplex',
             help='Generate a list of dictionaries with params from a multiplex file')

avocado/plugins/runner.py

@@ -23,6 +23,7 @@ from avocado.core import exit_codes
 from avocado.plugins import plugin
 from avocado.core import output
 from avocado import job
+from avocado import multiplexer
 
 
 class TestRunner(plugin.Plugin):
@@ -107,6 +108,7 @@ class TestRunner(plugin.Plugin):
                                      'present for the test. '
                                      'Current: False (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)')