simplify database fixture to the features we use

The Database fixture has existed for a long time, and has a large
amount of vestigial code that is no longer usable as it's masked by
other test setup. For instance, the conf fixture always sets the db
connection string to in memory db.

Simplify what the Database fixture is doing to just the inmemory
schema caching and reconstruction. Also provide a test case
demonstrating that this both sets up the db correctly, as well as
resets it after we've made changes.

Change-Id: Idc9b587c705c1c1ab4e1173ad1e8e244037284d7

nova/test.py

@@ -28,7 +28,6 @@ import copy
 import inspect
 import logging
 import os
-import shutil
 
 import fixtures
 from oslo.config import cfg
@@ -43,14 +42,11 @@ import testtools
 from nova.api.openstack import wsgi
 from nova import context
 from nova import db
-from nova.db import migration
-from nova.db.sqlalchemy import api as session
 from nova.network import manager as network_manager
 from nova import objects
 from nova.objects import base as objects_base
 from nova.openstack.common.fixture import logging as log_fixture
 from nova.openstack.common import log as nova_logging
-from nova import paths
 from nova import rpc
 from nova.tests import fixtures as nova_fixtures
 from nova.tests.unit import conf_fixture
@@ -58,14 +54,7 @@ from nova.tests.unit import policy_fixture
 from nova import utils
 
 
-test_opts = [
-    cfg.StrOpt('sqlite_clean_db',
-               default='clean.sqlite',
-               help='File name of clean sqlite db'),
-    ]
-
 CONF = cfg.CONF
-CONF.register_opts(test_opts)
 CONF.import_opt('enabled', 'nova.api.openstack', group='osapi_v3')
 CONF.set_override('use_stderr', False)
 
@@ -76,49 +65,9 @@ nova_logging.setup('nova')
 # tests that run at import time.
 objects.register_all()
 
-_DB_CACHE = None
 _TRUE_VALUES = ('True', 'true', '1', 'yes')
 
 
-class Database(fixtures.Fixture):
-
-    def __init__(self, db_session, db_migrate, sql_connection,
-                    sqlite_db, sqlite_clean_db):
-        self.sql_connection = sql_connection
-        self.sqlite_db = sqlite_db
-        self.sqlite_clean_db = sqlite_clean_db
-
-        self.engine = db_session.get_engine()
-        self.engine.dispose()
-        conn = self.engine.connect()
-        if sql_connection == "sqlite://":
-            if db_migrate.db_version() > db_migrate.db_initial_version():
-                return
-        else:
-            testdb = paths.state_path_rel(sqlite_db)
-            if os.path.exists(testdb):
-                return
-        db_migrate.db_sync()
-        if sql_connection == "sqlite://":
-            conn = self.engine.connect()
-            self._DB = "".join(line for line in conn.connection.iterdump())
-            self.engine.dispose()
-        else:
-            cleandb = paths.state_path_rel(sqlite_clean_db)
-            shutil.copyfile(testdb, cleandb)
-
-    def setUp(self):
-        super(Database, self).setUp()
-
-        if self.sql_connection == "sqlite://":
-            conn = self.engine.connect()
-            conn.connection.executescript(self._DB)
-            self.addCleanup(self.engine.dispose)
-        else:
-            shutil.copyfile(paths.state_path_rel(self.sqlite_clean_db),
-                            paths.state_path_rel(self.sqlite_db))
-
-
 class SampleNetworks(fixtures.Fixture):
 
     """Create sample networks in the database."""
@@ -266,14 +215,7 @@ class TestCase(testtools.TestCase):
         rpc.init(CONF)
 
         if self.USES_DB:
-            global _DB_CACHE
-            if not _DB_CACHE:
-                _DB_CACHE = Database(session, migration,
-                        sql_connection=CONF.database.connection,
-                        sqlite_db=CONF.database.sqlite_db,
-                        sqlite_clean_db=CONF.sqlite_clean_db)
-
-            self.useFixture(_DB_CACHE)
+            self.useFixture(nova_fixtures.Database())
 
         # NOTE(danms): Make sure to reset us back to non-remote objects
         # for each test to avoid interactions. Also, backup the object

nova/tests/fixtures.py

@@ -23,11 +23,17 @@ import os
 import uuid
 
 import fixtures
+from oslo.config import cfg
 
+from nova.db import migration
+from nova.db.sqlalchemy import api as session
 from nova import service
 
 _TRUE_VALUES = ('True', 'true', '1', 'yes')
 
+CONF = cfg.CONF
+DB_SCHEMA = ""
+
 
 class ServiceFixture(fixtures.Fixture):
     """Run a service as a test fixture."""
@@ -189,3 +195,25 @@ class Timeout(fixtures.Fixture):
         super(Timeout, self).setUp()
         if self.test_timeout > 0:
             self.useFixture(fixtures.Timeout(self.test_timeout, gentle=True))
+
+
+class Database(fixtures.Fixture):
+    def _cache_schema(self):
+        global DB_SCHEMA
+        if not DB_SCHEMA:
+            engine = session.get_engine()
+            conn = engine.connect()
+            migration.db_sync()
+            DB_SCHEMA = "".join(line for line in conn.connection.iterdump())
+            engine.dispose()
+
+    def reset(self):
+        self._cache_schema()
+        engine = session.get_engine()
+        engine.dispose()
+        conn = engine.connect()
+        conn.connection.executescript(DB_SCHEMA)
+
+    def setUp(self):
+        super(Database, self).setUp()
+        self.reset()