From e60114c716ac78ff3826c68dd8e1f0de1e822015 Mon Sep 17 00:00:00 2001
From: Calen Pennington <cale@edx.org>
Date: Mon, 16 May 2016 07:32:09 -0400
Subject: [PATCH] Add paver arguments to control concurrency and randomization

---
 docs/en_us/internal/testing.rst         | 12 +++++++
 pavelib/tests.py                        |  5 +++
 pavelib/utils/test/suites/nose_suite.py | 46 +++++++++++++------------
 3 files changed, 41 insertions(+), 22 deletions(-)

diff --git a/docs/en_us/internal/testing.rst b/docs/en_us/internal/testing.rst
index ec86638db2..a074be9a26 100644
--- a/docs/en_us/internal/testing.rst
+++ b/docs/en_us/internal/testing.rst
@@ -208,6 +208,18 @@ To run a single test format the command like this.
 
     paver test_system -t lms/djangoapps/courseware/tests/tests.py:ActivateLoginTest.test_activate_login
 
+The ``lms`` suite of tests runs concurrently, and with randomized order, by default.
+You can override these by using ``--no-randomize`` to disable randomization,
+and ``--processes=N`` to control how many tests will run concurrently (``0`` will
+disable concurrency). For example:
+
+::
+    # This will run all tests in the order that they appear in their files, serially
+    paver test_system -s lms --no-randomize --processes=0
+
+    # This will run using only 2 processes for tests
+    paver test_system -s lms --processes=2
+
 To re-run all failing django tests from lms or cms, use the
 ``--failed``,\ ``-f`` flag (see note at end of section).
 
diff --git a/pavelib/tests.py b/pavelib/tests.py
index 61ca58f5f0..e1bde07e39 100644
--- a/pavelib/tests.py
+++ b/pavelib/tests.py
@@ -31,6 +31,9 @@ __test__ = False  # do not collect
     ('extra_args=', 'e', 'adds as extra args to the test command'),
     ('cov_args=', 'c', 'adds as args to coverage for the test run'),
     ('skip_clean', 'C', 'skip cleaning repository before running tests'),
+    ('processes=', 'p', 'number of processes to use running tests'),
+    make_option('-r', '--randomize', action='store_true', dest='randomize', help='run the tests in a random order'),
+    make_option('--no-randomize', action='store_false', dest='randomize', help="don't run the tests in a random order"),
     make_option("--verbose", action="store_const", const=2, dest="verbosity"),
     make_option("-q", "--quiet", action="store_const", const=0, dest="verbosity"),
     make_option("-v", "--verbosity", action="count", dest="verbosity", default=1),
@@ -59,6 +62,8 @@ def test_system(options):
         'skip_clean': getattr(options, 'skip_clean', False),
         'pdb': getattr(options, 'pdb', False),
         'disable_migrations': getattr(options, 'disable_migrations', False),
+        'processes': getattr(options, 'processes', None),
+        'randomize': getattr(options, 'randomize', None),
     }
 
     if test_id:
diff --git a/pavelib/utils/test/suites/nose_suite.py b/pavelib/utils/test/suites/nose_suite.py
index f5557f6fc5..6243fe5c80 100644
--- a/pavelib/utils/test/suites/nose_suite.py
+++ b/pavelib/utils/test/suites/nose_suite.py
@@ -113,36 +113,38 @@ class SystemTestSuite(NoseTestSuite):
         self.test_id = kwargs.get('test_id', self._default_test_id)
         self.fasttest = kwargs.get('fasttest', False)
 
+        self.processes = kwargs.get('processes', None)
+        self.randomize = kwargs.get('randomize', None)
+
     def __enter__(self):
         super(SystemTestSuite, self).__enter__()
 
     @property
     def cmd(self):
-        cmd = (
-            './manage.py {system} test --verbosity={verbosity} '
-            '{test_id} {test_opts} --settings=test {system_opts} {extra} '
-            '--with-xunitmp --xunitmp-file={xunit_report}'.format(
-                system=self.root,
-                verbosity=self.verbosity,
-                test_id=self.test_id,
-                test_opts=self.test_options_flags,
-                system_opts=self._system_options,
-                extra=self.extra_args,
-                xunit_report=self.report_dir / "nosetests.xml",
-            )
-        )
+        if self.processes is None:
+            # Use one process per core for LMS tests, and no multiprocessing
+            # otherwise.
+            self.processes = -1 if self.root == 'lms' else 0
 
-        return self._under_coverage_cmd(cmd)
+        if self.randomize is None:
+            self.randomize = self.root == 'lms'
 
-    @property
-    def _system_options(self):
-        """
-        Test arguments that are only enabled for specific systems.
-        """
-        if self.root == 'lms':
-            return '--with-randomly --with-database-isolation --processes=-1'
+        cmd = [
+            './manage.py', self.root, 'test',
+            '--verbosity={}'.format(self.verbosity),
+            self.test_id,
+            self.test_options_flags,
+            '--settings=test',
+            self.extra_args,
+            '--with-xunitmp',
+            '--xunitmp-file={}'.format(self.report_dir / "nosetests.xml"),
+            '--processes={}'.format(self.processes),
+            '--with-database-isolation',
+        ]
+        if self.randomize:
+            cmd.append('--with-randomly')
 
-        return ''
+        return self._under_coverage_cmd(" ".join(cmd))
 
     @property
     def _default_test_id(self):