Allow more time for DB migration tests

Adopt the timeout override fixture from nova.

Borrowed from I591f3c270804dfb01eab7c8c5d43b87a7abcdeda
Co-Authored-By: Sean Dague <sean@dague.net>

Closes-Bug: #1626277

Change-Id: I0b40ce97ba42d55f048e9728d9f032ada5c85100

.testr.conf

@@ -1,4 +1,8 @@
 [DEFAULT]
-test_command=OS_STDOUT_CAPTURE=1 OS_STDERR_CAPTURE=1 OS_LOG_CAPTURE=1 ${PYTHON:-python} -m subunit.run discover -t ./ ${OS_TEST_PATH:-./neutron/tests/unit} $LISTOPT $IDOPTION
+test_command=OS_STDOUT_CAPTURE=${OS_STDOUT_CAPTURE:-1} \
+             OS_STDERR_CAPTURE=${OS_STDERR_CAPTURE:-1} \
+             OS_LOG_CAPTURE=${OS_LOG_CAPTURE:-1} \
+             OS_TEST_TIMEOUT=${OS_TEST_TIMEOUT:-160} \
+             ${PYTHON:-python} -m subunit.run discover -t ./ ${OS_TEST_PATH:-./neutron/tests/unit} $LISTOPT $IDOPTION
 test_id_option=--load-list $IDFILE
 test_list_option=--list

neutron/tests/base.py

@@ -426,3 +426,34 @@ class PluginFixture(fixtures.Fixture):
             if plugin() and not isinstance(plugin(), mock.Base):
                 raise AssertionError(
                     'The plugin for this test was not deallocated.')
+
+
+class Timeout(fixtures.Fixture):
+    """Setup per test timeouts.
+
+    In order to avoid test deadlocks we support setting up a test
+    timeout parameter read from the environment. In almost all
+    cases where the timeout is reached this means a deadlock.
+
+    A scaling factor allows extremely long tests to specify they
+    need more time.
+    """
+
+    def __init__(self, timeout=None, scaling=1):
+        super(Timeout, self).__init__()
+        if timeout is None:
+            timeout = os.environ.get('OS_TEST_TIMEOUT', 0)
+        try:
+            self.test_timeout = int(timeout)
+        except ValueError:
+            # If timeout value is invalid do not set a timeout.
+            self.test_timeout = 0
+        if scaling >= 1:
+            self.test_timeout *= scaling
+        else:
+            raise ValueError('scaling value must be >= 1')
+
+    def setUp(self):
+        super(Timeout, self).setUp()
+        if self.test_timeout > 0:
+            self.useFixture(fixtures.Timeout(self.test_timeout, gentle=True))

neutron/tests/functional/db/test_migrations.py

@@ -30,6 +30,7 @@ import subprocess
 from neutron.db.migration.alembic_migrations import external
 from neutron.db.migration import cli as migration
 from neutron.db.migration.models import head as head_models
+from neutron.tests import base as test_base
 from neutron.tests.unit import testlib_api
 
 cfg.CONF.import_opt('core_plugin', 'neutron.conf.common')
@@ -129,6 +130,7 @@ class _TestModelsMigrations(test_migrations.ModelsMigrationsSync):
     '''
 
     BUILD_SCHEMA = False
+    TIMEOUT_SCALING_FACTOR = 4
 
     def setUp(self):
         super(_TestModelsMigrations, self).setUp()
@@ -137,6 +139,9 @@ class _TestModelsMigrations(test_migrations.ModelsMigrationsSync):
         self.alembic_config = migration.get_neutron_config()
         self.alembic_config.neutron_config = cfg.CONF
 
+        # Migration tests can take a long time
+        self.useFixture(test_base.Timeout(scaling=self.TIMEOUT_SCALING_FACTOR))
+
     def db_sync(self, engine):
         upgrade(engine, self.alembic_config)