Extend timeout for database migration tests

Database migration tests (specifically test_walk_versions
and test_mysql_innodb) are failing due to multiple reasons
from oslo.db side mentioned in the code comments.
Increasing the timeout will allow the tests to execute
successfully on slower nodes.
This solution is adopted from manila [1] and also implemented
in neutron [2] for the same and hopefully they're not facing the
issue currently.

[1] https://review.openstack.org/#/c/291397/
[2] https://review.openstack.org/#/c/610003/

Change-Id: I31bdcfc12e3b8b54d5b5a6664f88df3b7dcd4fc0

cinder/tests/unit/db/test_migrations.py

@@ -34,6 +34,7 @@ from sqlalchemy.engine import reflection
 
 from cinder.db import migration
 import cinder.db.sqlalchemy.migrate_repo
+from cinder.tests.unit import utils as test_utils
 
 
 class MigrationsMixin(test_migrations.WalkVersionsMixin):
@@ -348,6 +349,10 @@ class MigrationsMixin(test_migrations.WalkVersionsMixin):
         self.assertIn('destination_project_id', volume_transfer.c)
         self.assertIn('accepted', volume_transfer.c)
 
+    # NOTE: this test becomes slower with each addition of new DB migration.
+    # 'pymysql' works much slower on slow nodes than 'psycopg2'. And such
+    # timeout mostly required for testing of 'mysql' backend.
+    @test_utils.set_timeout(300)
     def test_walk_versions(self):
         self.walk_versions(False, False)
         self.assert_each_foreign_key_is_part_of_an_index()
@@ -371,6 +376,7 @@ class TestMysqlMigrations(test_fixtures.OpportunisticDBTestMixin,
     FIXTURE = test_fixtures.MySQLOpportunisticFixture
     BOOL_TYPE = sqlalchemy.dialects.mysql.TINYINT
 
+    @test_utils.set_timeout(300)
     def test_mysql_innodb(self):
         """Test that table creation on mysql only builds InnoDB tables."""
         # add this to the global lists to make reset work with it, it's removed

cinder/tests/unit/utils.py

@@ -14,6 +14,7 @@
 #
 
 import datetime
+import fixtures
 import socket
 import sys
 import uuid
@@ -23,6 +24,7 @@ from oslo_config import cfg
 from oslo_service import loopingcall
 from oslo_utils import timeutils
 import oslo_versionedobjects
+import six
 
 from cinder.common import constants
 from cinder import context
@@ -534,3 +536,23 @@ def create_populated_cluster(ctxt, num_services, num_down_svcs=0, **values):
         for i in range(num_services)
     ]
     return cluster, svcs
+
+
+def set_timeout(timeout):
+    """Timeout decorator for unit test methods.
+
+    Use this decorator for tests that are expected to pass in very specific
+    amount of time, not common for all other tests.
+    It can have either big or small value.
+    """
+
+    def _decorator(f):
+
+        @six.wraps(f)
+        def _wrapper(self, *args, **kwargs):
+            self.useFixture(fixtures.Timeout(timeout, gentle=True))
+            return f(self, *args, **kwargs)
+
+        return _wrapper
+
+    return _decorator