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

@@ -37,13 +37,18 @@ import collections
 import os
 import re
 
-import yaml
-
-
 try:
-    from yaml import CLoader as Loader
+    import yaml
 except ImportError:
-    from yaml import Loader
+    MULTIPLEX_CAPABLE = False
+else:
+    MULTIPLEX_CAPABLE = True
+
+if MULTIPLEX_CAPABLE:
+    try:
+        from yaml import CLoader as Loader
+    except ImportError:
+        from yaml import Loader
 
 
 # Mapping for yaml flags

avocado/job.py

@@ -90,7 +90,8 @@ class Job(object):
                 self.loglevel = mapping[raw_log_level]
             else:
                 self.loglevel = logging.DEBUG
-            self.multiplex_files = args.multiplex_files
+            if multiplexer.MULTIPLEX_CAPABLE:
+                self.multiplex_files = args.multiplex_files
             self.show_job_log = args.show_job_log
             self.silent = args.silent
         else:
@@ -259,13 +260,14 @@ class Job(object):
 
         params_list = self.test_loader.discover_urls(urls)
 
-        if multiplex_files is None:
-            if self.args and self.args.multiplex_files is not None:
-                multiplex_files = self.args.multiplex_files
+        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
 
-        if multiplex_files is not None:
-            params_list = self._multiplex_params_list(params_list,
-                                                      multiplex_files)
+            if multiplex_files is not None:
+                params_list = self._multiplex_params_list(params_list,
+                                                          multiplex_files)
 
         try:
             test_suite = self.test_loader.discover(params_list)

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):
@@ -107,13 +108,14 @@ class TestRunner(plugin.Plugin):
                                      'present for the test. '
                                      'Current: False (output check enabled)'))
 
-        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)')
-        mux.add_argument('--filter-only', nargs='*', default=[],
-                         help='Filter only path(s) from multiplexing')
-        mux.add_argument('--filter-out', nargs='*', default=[],
-                         help='Filter out path(s) from multiplexing')
+        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)')
+            mux.add_argument('--filter-only', nargs='*', default=[],
+                             help='Filter only path(s) from multiplexing')
+            mux.add_argument('--filter-out', nargs='*', default=[],
+                             help='Filter out path(s) from multiplexing')
 
         super(TestRunner, self).configure(self.parser)
         # Export the test runner parser back to the main parser