launcher: Allow partionning the tests

This introduce new command line options, --parts and --part-index. When
--parts is set to a value larger then 1, the tests will be split in the
same number of group. The group number identified by --part-index will
be executed.

This is being added in orther to support gliblab CI parallel feature.

validate/launcher/baseclasses.py

@@ -40,6 +40,7 @@ import xml
 import random
 import shutil
 import uuid
+from itertools import cycle
 
 from .utils import which
 from . import reporters
@@ -1866,6 +1867,13 @@ class _TestsLauncher(Loggable):
 
         return testlist_changed
 
+    def _split_tests(self, num_groups):
+        groups = [[] for x in range(num_groups)]
+        group = cycle(groups)
+        for test in self.tests:
+            next(group).append(test)
+        return groups
+
     def list_tests(self):
         for tester in self.testers:
             if not self._tester_needed(tester):
@@ -1878,6 +1886,15 @@ class _TestsLauncher(Loggable):
 
             self.tests.extend(tests)
         self.tests.sort(key=lambda test: test.classname)
+
+        if self.options.num_parts < 1:
+            raise RuntimeError("Tests must be split in positive number of parts.")
+        if self.options.num_parts > len(self.tests):
+            raise RuntimeError("Cannot have more parts then there exist tests.")
+        if self.options.part_index < 1 or self.options.part_index > self.options.num_parts:
+            raise RuntimeError("Part index is out of range")
+
+        self.tests = self._split_tests(self.options.num_parts)[self.options.part_index - 1]
         return self.tests
 
     def _tester_needed(self, tester):

validate/launcher/main.py

@@ -530,6 +530,13 @@ class LauncherConfig(Loggable):
         dir_group.add_argument("--ignore-numfailures", dest="ignore_numfailures",
                                help="Ignore the number of failed test in exit code",
                                default=False, action='store_true')
+        dir_group.add_argument("--parts", dest="num_parts",
+                               help="Splits the tests in equally distributed parts and only run one part"
+                               " (Defaults to 1 part)",
+                               type=int, default=1)
+        dir_group.add_argument("--part-index", dest="part_index",
+                               help="The index of the part to be run (starts at 1).",
+                               type=int, default=1)
 
         http_server_group = parser.add_argument_group(
             "Handle the HTTP server to be created")