From 09dc884c38b0cc94add17397f7fff8c9ed57efe8 Mon Sep 17 00:00:00 2001
From: Calen Pennington <cale@edx.org>
Date: Wed, 4 May 2016 14:33:42 -0400
Subject: [PATCH] Isolate databases between test processes

---
 cms/envs/test.py                        |  4 ++++
 lms/envs/test.py                        |  6 ++++--
 openedx/core/djangolib/testing/utils.py | 20 ++++++++++++++++++++
 scripts/generic-ci-tests.sh             | 11 ++++++-----
 4 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/cms/envs/test.py b/cms/envs/test.py
index 18bf787368..ce5f618b2e 100644
--- a/cms/envs/test.py
+++ b/cms/envs/test.py
@@ -57,6 +57,10 @@ NOSE_ARGS = [
     '--xunit-file', _REPORT_DIR / 'nosetests.xml',
 ]
 
+NOSE_PLUGINS = [
+    'openedx.core.djangolib.testing.utils.NoseDatabaseIsolation'
+]
+
 TEST_ROOT = path('test_root')
 
 # Want static files in the same dir for running on jenkins.
diff --git a/lms/envs/test.py b/lms/envs/test.py
index 344a9ddc47..cda9f23b46 100644
--- a/lms/envs/test.py
+++ b/lms/envs/test.py
@@ -99,6 +99,10 @@ NOSE_ARGS = [
     '--xunit-file', _REPORT_DIR / 'nosetests.xml',
 ]
 
+NOSE_PLUGINS = [
+    'openedx.core.djangolib.testing.utils.NoseDatabaseIsolation'
+]
+
 # Local Directories
 TEST_ROOT = path("test_root")
 # Want static files in the same dir for running on jenkins.
@@ -181,12 +185,10 @@ CONTENTSTORE = {
 DATABASES = {
     'default': {
         'ENGINE': 'django.db.backends.sqlite3',
-        'NAME': TEST_ROOT / 'db' / 'edx.db',
         'ATOMIC_REQUESTS': True,
     },
     'student_module_history': {
         'ENGINE': 'django.db.backends.sqlite3',
-        'NAME': TEST_ROOT / 'db' / 'student_module_history.db'
     },
 }
 
diff --git a/openedx/core/djangolib/testing/utils.py b/openedx/core/djangolib/testing/utils.py
index 5a6efbfaa0..512beec7d9 100644
--- a/openedx/core/djangolib/testing/utils.py
+++ b/openedx/core/djangolib/testing/utils.py
@@ -10,11 +10,14 @@ Utility classes for testing django applications.
 
 import copy
 
+from django import db
 from django.core.cache import caches
 from django.test import TestCase, override_settings
 from django.conf import settings
 from django.contrib import sites
 
+from nose.plugins import Plugin
+
 from request_cache.middleware import RequestCache
 
 
@@ -138,3 +141,20 @@ class CacheIsolationTestCase(CacheIsolationMixin, TestCase):
 
         self.clear_caches()
         self.addCleanup(self.clear_caches)
+
+
+class NoseDatabaseIsolation(Plugin):
+    """
+    nosetest plugin that resets django databases before any tests begin.
+
+    Used to make sure that tests running in multi processes aren't sharing
+    a database connection.
+    """
+    name = "database-isolation"
+
+    def begin(self):
+        """
+        Before any tests start, reset all django database connections.
+        """
+        for db_ in db.connections.all():
+            db_.close()
diff --git a/scripts/generic-ci-tests.sh b/scripts/generic-ci-tests.sh
index 64bb98f011..df155dfcd8 100755
--- a/scripts/generic-ci-tests.sh
+++ b/scripts/generic-ci-tests.sh
@@ -97,21 +97,22 @@ case "$TEST_SUITE" in
         ;;
 
     "lms-unit")
+        LMS_ARGS="--with-flaky"
         case "$SHARD" in
             "all")
-                paver test_system -s lms --extra_args="--with-flaky" --cov_args="-p"
+                paver test_system -s lms --extra_args="$LMS_ARGS" --cov_args="-p" -v
                 ;;
             "1")
-                paver test_system -s lms --extra_args="--attr='shard_1' --with-flaky" --cov_args="-p" -v
+                paver test_system -s lms --extra_args="--attr='shard_1' $LMS_ARGS" --cov_args="-p" -v
                 ;;
             "2")
-                paver test_system -s lms --extra_args="--attr='shard_2' --with-flaky" --cov_args="-p" -v
+                paver test_system -s lms --extra_args="--attr='shard_2' $LMS_ARGS" --cov_args="-p" -v
                 ;;
             "3")
-                paver test_system -s lms --extra_args="--attr='shard_3' --with-flaky" --cov_args="-p" -v
+                paver test_system -s lms --extra_args="--attr='shard_3' $LMS_ARGS" --cov_args="-p" -v
                 ;;
             "4")
-                paver test_system -s lms --extra_args="--attr='shard_1=False,shard_2=False,shard_3=False' --with-flaky" --cov_args="-p" -v
+                paver test_system -s lms --extra_args="--attr='shard_1=False,shard_2=False,shard_3=False' $LMS_ARGS" --cov_args="-p" -v
                 ;;
             *)
                 # If no shard is specified, rather than running all tests, create an empty xunit file. This is a