Merge "Enhanced fixtures for enginefacade-based provisioning"

19 files changed, 916 insertions, 39 deletions

diff --git a/oslo_db/sqlalchemy/enginefacade.py b/oslo_db/sqlalchemy/enginefacade.py
index cd5d74b..d4ba4cc 100644
--- a/oslo_db/sqlalchemy/enginefacade.py
+++ b/oslo_db/sqlalchemy/enginefacade.py
@@ -262,6 +262,46 @@ class _TransactionFactory(object):
 
         return self._legacy_facade
 
+    def get_writer_engine(self):
+        """Return the writer engine for this factory.
+
+        Implies start.
+
+        """
+        if not self._started:
+            self._start()
+        return self._writer_engine
+
+    def get_reader_engine(self):
+        """Return the reader engine for this factory.
+
+        Implies start.
+
+        """
+        if not self._started:
+            self._start()
+        return self._reader_engine
+
+    def get_writer_maker(self):
+        """Return the writer sessionmaker for this factory.
+
+        Implies start.
+
+        """
+        if not self._started:
+            self._start()
+        return self._writer_maker
+
+    def get_reader_maker(self):
+        """Return the reader sessionmaker for this factory.
+
+        Implies start.
+
+        """
+        if not self._started:
+            self._start()
+        return self._reader_maker
+
     def _create_connection(self, mode):
         if not self._started:
             self._start()
@@ -666,6 +706,36 @@ class _TransactionContextManager(object):
 
         return self._factory.get_legacy_facade()
 
+    def get_engine(self):
+        """Return the Engine in use.
+
+        This will be based on the state being WRITER or READER.
+
+        This implies a start operation.
+
+        """
+        if self._mode is _WRITER:
+            return self._factory.get_writer_engine()
+        elif self._mode is _READER:
+            return self._factory.get_reader_engine()
+        else:
+            raise ValueError("mode should be WRITER or READER")
+
+    def get_sessionmaker(self):
+        """Return the sessionmaker in use.
+
+        This will be based on the state being WRITER or READER.
+
+        This implies a start operation.
+
+        """
+        if self._mode is _WRITER:
+            return self._factory.get_writer_maker()
+        elif self._mode is _READER:
+            return self._factory.get_reader_maker()
+        else:
+            raise ValueError("mode should be WRITER or READER")
+
     def dispose_pool(self):
         """Call engine.pool.dispose() on underlying Engine objects."""
         self._factory.dispose_pool()
diff --git a/oslo_db/sqlalchemy/provision.py b/oslo_db/sqlalchemy/provision.py
index 8ae9d0a..a1e1d19 100644
--- a/oslo_db/sqlalchemy/provision.py
+++ b/oslo_db/sqlalchemy/provision.py
@@ -76,14 +76,24 @@ class Schema(object):
 
 
 class BackendResource(testresources.TestResourceManager):
-    def __init__(self, database_type):
+    def __init__(self, database_type, ad_hoc_url=None):
         super(BackendResource, self).__init__()
         self.database_type = database_type
         self.backend = Backend.backend_for_database_type(self.database_type)
+        self.ad_hoc_url = ad_hoc_url
+        if ad_hoc_url is None:
+            self.backend = Backend.backend_for_database_type(
+                self.database_type)
+        else:
+            self.backend = Backend(self.database_type, ad_hoc_url)
+            self.backend._verify()
 
     def make(self, dependency_resources):
         return self.backend
 
+    def clean(self, resource):
+        self.backend._dispose()
+
     def isDirty(self):
         return False
 
@@ -100,9 +110,11 @@ class DatabaseResource(testresources.TestResourceManager):
 
     """
 
-    def __init__(self, database_type, _enginefacade=None):
+    def __init__(self, database_type, _enginefacade=None,
+                 provision_new_database=False, ad_hoc_url=None):
         super(DatabaseResource, self).__init__()
         self.database_type = database_type
+        self.provision_new_database = provision_new_database
 
         # NOTE(zzzeek) the _enginefacade is an optional argument
         # here in order to accomodate Neutron's current direct use
@@ -114,38 +126,42 @@ class DatabaseResource(testresources.TestResourceManager):
         else:
             self._enginefacade = enginefacade._context_manager
         self.resources = [
-            ('backend', BackendResource(database_type))
+            ('backend', BackendResource(database_type, ad_hoc_url))
         ]
 
     def make(self, dependency_resources):
         backend = dependency_resources['backend']
         _enginefacade = self._enginefacade.make_new_manager()
 
-        db_token = _random_ident()
-        url = backend.provisioned_database_url(db_token)
+        if self.provision_new_database:
+            db_token = _random_ident()
+            url = backend.provisioned_database_url(db_token)
+            LOG.info(
+                "CREATE BACKEND %s TOKEN %s", backend.engine.url, db_token)
+            backend.create_named_database(db_token, conditional=True)
+        else:
+            db_token = None
+            url = backend.url
 
         _enginefacade.configure(
             logging_name="%s@%s" % (self.database_type, db_token))
 
-        LOG.info(
-            "CREATE BACKEND %s TOKEN %s", backend.engine.url, db_token)
-        backend.create_named_database(db_token, conditional=True)
-
         _enginefacade._factory._start(connection=url)
         engine = _enginefacade._factory._writer_engine
         return ProvisionedDatabase(backend, _enginefacade, engine, db_token)
 
     def clean(self, resource):
-        resource.engine.dispose()
-        LOG.info(
-            "DROP BACKEND %s TOKEN %s",
-            resource.backend.engine, resource.db_token)
-        resource.backend.drop_named_database(resource.db_token)
+        if self.provision_new_database:
+            LOG.info(
+                "DROP BACKEND %s TOKEN %s",
+                resource.backend.engine, resource.db_token)
+            resource.backend.drop_named_database(resource.db_token)
 
     def isDirty(self):
         return False
 
 
+@debtcollector.removals.removed_class("TransactionResource")
 class TransactionResource(testresources.TestResourceManager):
 
     def __init__(self, database_resource, schema_resource):
@@ -299,6 +315,10 @@ class Backend(object):
                 conn.close()
                 return eng
 
+    def _dispose(self):
+        """Dispose main resources of this backend."""
+        self.impl.dispose(self.engine)
+
     def create_named_database(self, ident, conditional=False):
         """Create a database with the given name."""
 
@@ -400,6 +420,10 @@ class BackendImpl(object):
 
     supports_drop_fk = True
 
+    def dispose(self, engine):
+        LOG.info("DISPOSE ENGINE %s", engine)
+        engine.dispose()
+
     @classmethod
     def all_impls(cls):
         """Return an iterator of all possible BackendImpl objects.
@@ -567,6 +591,17 @@ class SQLiteBackendImpl(BackendImpl):
 
     supports_drop_fk = False
 
+    def dispose(self, engine):
+        LOG.info("DISPOSE ENGINE %s", engine)
+        engine.dispose()
+        url = engine.url
+        self._drop_url_file(url, True)
+
+    def _drop_url_file(self, url, conditional):
+        filename = url.database
+        if filename and (not conditional or os.access(filename, os.F_OK)):
+            os.remove(filename)
+
     def create_opportunistic_driver_url(self):
         return "sqlite://"
 
diff --git a/oslo_db/sqlalchemy/test_base.py b/oslo_db/sqlalchemy/test_base.py
index f25d266..a28259e 100644
--- a/oslo_db/sqlalchemy/test_base.py
+++ b/oslo_db/sqlalchemy/test_base.py
@@ -13,6 +13,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import debtcollector
 import fixtures
 import testresources
 import testscenarios
@@ -35,6 +36,7 @@ from oslo_db.sqlalchemy import provision
 from oslo_db.sqlalchemy import session
 
 
+@debtcollector.removals.removed_class("DbFixture")
 class DbFixture(fixtures.Fixture):
     """Basic database fixture.
 
@@ -90,6 +92,7 @@ class DbFixture(fixtures.Fixture):
         self.addCleanup(self.test.enginefacade.dispose_global)
 
 
+@debtcollector.removals.removed_class("DbTestCase")
 class DbTestCase(test_base.BaseTestCase):
     """Base class for testing of DB code.
 
@@ -191,6 +194,7 @@ class DbTestCase(test_base.BaseTestCase):
                 "implemented within generate_schema().")
 
 
+@debtcollector.removals.removed_class("OpportunisticTestCase")
 class OpportunisticTestCase(DbTestCase):
     """Placeholder for backwards compatibility."""
 
@@ -220,18 +224,22 @@ def backend_specific(*dialects):
     return wrap
 
 
+@debtcollector.removals.removed_class("MySQLOpportunisticFixture")
 class MySQLOpportunisticFixture(DbFixture):
     DRIVER = 'mysql'
 
 
+@debtcollector.removals.removed_class("PostgreSQLOpportunisticFixture")
 class PostgreSQLOpportunisticFixture(DbFixture):
     DRIVER = 'postgresql'
 
 
+@debtcollector.removals.removed_class("MySQLOpportunisticTestCase")
 class MySQLOpportunisticTestCase(OpportunisticTestCase):
     FIXTURE = MySQLOpportunisticFixture
 
 
+@debtcollector.removals.removed_class("PostgreSQLOpportunisticTestCase")
 class PostgreSQLOpportunisticTestCase(OpportunisticTestCase):
     FIXTURE = PostgreSQLOpportunisticFixture
 
diff --git a/oslo_db/sqlalchemy/test_fixtures.py b/oslo_db/sqlalchemy/test_fixtures.py
new file mode 100644
index 0000000..8b35ac3
--- /dev/null
+++ b/oslo_db/sqlalchemy/test_fixtures.py
@@ -0,0 +1,546 @@
+# Copyright (c) 2016 OpenStack Foundation
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import fixtures
+import logging
+import testresources
+
+from oslo_db import exception
+from oslo_db.sqlalchemy import enginefacade
+from oslo_db.sqlalchemy import provision
+from oslo_db.sqlalchemy import utils
+
+
+LOG = logging.getLogger(__name__)
+
+
+class ReplaceEngineFacadeFixture(fixtures.Fixture):
+    """A fixture that will plug the engine of one enginefacade into another.
+
+    This fixture can be used by test suites that already have their own non-
+    oslo_db database setup / teardown schemes, to plug any URL or test-oriented
+    enginefacade as-is into an enginefacade-oriented API.
+
+    For applications that use oslo.db's testing fixtures, the
+    ReplaceEngineFacade fixture is used internally.
+
+    E.g.::
+
+        class MyDBTest(TestCase):
+
+            def setUp(self):
+                from myapplication.api import main_enginefacade
+
+                my_test_enginefacade = enginefacade.transaction_context()
+                my_test_enginefacade.configure(connection=my_test_url)
+
+                self.useFixture(
+                    ReplaceEngineFacadeFixture(
+                        main_enginefacade, my_test_enginefacade))
+
+    Above, the main_enginefacade object is the normal application level
+    one, and my_test_enginefacade is a local one that we've created to
+    refer to some testing database.   Throughout the fixture's setup,
+    the application level enginefacade will use the engine factory and
+    engines of the testing enginefacade, and at fixture teardown will be
+    replaced back.
+
+    """
+    def __init__(self, enginefacade, replace_with_enginefacade):
+        super(ReplaceEngineFacadeFixture, self).__init__()
+        self.enginefacade = enginefacade
+        self.replace_with_enginefacade = replace_with_enginefacade
+
+    def _setUp(self):
+        _reset_facade = self.enginefacade.patch_factory(
+            self.replace_with_enginefacade._factory
+        )
+        self.addCleanup(_reset_facade)
+
+
+class BaseDbFixture(fixtures.Fixture):
+    """Base database provisioning fixture.
+
+    This serves as the base class for the other fixtures, but by itself
+    does not implement _setUp(). It provides the basis for the flags
+    implemented by the various capability mixins (GenerateSchema,
+    DeletesFromSchema, etc.) as well as providing an abstraction over
+    the provisioning objects, which are specific to testresources.
+    Overall, consumers of this fixture just need to use the right classes
+    and the testresources mechanics are taken care of.
+
+    """
+    DRIVER = "sqlite"
+
+    _DROP_SCHEMA_PER_TEST = True
+    _BUILD_SCHEMA = False
+    _BUILD_WITH_MIGRATIONS = False
+
+    _database_resources = {}
+    _db_not_available = {}
+    _schema_resources = {}
+
+    def __init__(self, driver=None, ident=None):
+        super(BaseDbFixture, self).__init__()
+        self.driver = driver or self.DRIVER
+        self.ident = ident or "default"
+        self.resource_key = (self.driver, self.__class__, self.ident)
+
+    def get_enginefacade(self):
+        """Return an enginefacade._TransactionContextManager.
+
+        This is typically a global variable like "context_manager" declared
+        in the db/api.py module and is the object returned by
+        enginefacade.transaction_context().
+
+        If left not implemented, the global enginefacade manager is used.
+
+        For the case where a project uses per-object or per-test enginefacades
+        like Gnocchi, the get_per_test_enginefacade()
+        method should also be implemented.
+
+
+        """
+        return enginefacade._context_manager
+
+    def get_per_test_enginefacade(self):
+        """Return an enginefacade._TransactionContextManager per test.
+
+        This facade should be the one that the test expects the code to
+        use.   Usually this is the same one returned by get_engineafacade()
+        which is the default.  For special applications like Gnocchi,
+        this can be overridden to provide an instance-level facade.
+
+        """
+        return self.get_enginefacade()
+
+    def _get_db_resource_not_available_reason(self):
+        return self._db_not_available.get(self.resource_key, None)
+
+    def _has_db_resource(self):
+        return self._database_resources.get(
+            self.resource_key, None) is not None
+
+    def _generate_schema_resource(self, database_resource):
+        return provision.SchemaResource(
+            database_resource,
+            None if not self._BUILD_SCHEMA
+            else self.generate_schema_create_all
+            if not self._BUILD_WITH_MIGRATIONS
+            else self.generate_schema_migrations,
+            self._DROP_SCHEMA_PER_TEST
+        )
+
+    def _get_resources(self):
+        key = self.resource_key
+
+        # the DatabaseResource and SchemaResource provision objects
+        # can be used by testresources as a marker outside of an individual
+        # test to indicate that this database / schema can be used across
+        # multiple tests.   To make this work, many instances of this
+        # fixture have to return the *same* resource object given the same
+        # inputs.  so we cache these in class-level dictionaries.
+
+        if key not in self._database_resources:
+            _enginefacade = self.get_enginefacade()
+            try:
+                self._database_resources[key] = \
+                    self._generate_database_resource(_enginefacade)
+            except exception.BackendNotAvailable as bne:
+                self._database_resources[key] = None
+                self._db_not_available[key] = str(bne)
+
+        database_resource = self._database_resources[key]
+
+        if database_resource is None:
+            return []
+        else:
+            if key in self._schema_resources:
+                schema_resource = self._schema_resources[key]
+            else:
+                schema_resource = self._schema_resources[key] = \
+                    self._generate_schema_resource(database_resource)
+
+            return [
+                ('_schema_%s' % self.ident, schema_resource),
+                ('_db_%s' % self.ident, database_resource)
+            ]
+
+
+class GeneratesSchema(object):
+    """Mixin defining a fixture as generating a schema using create_all().
+
+    This is a "capability" mixin that works in conjunction with classes
+    that include BaseDbFixture as a base.
+
+    """
+
+    _BUILD_SCHEMA = True
+    _BUILD_WITH_MIGRATIONS = False
+
+    def generate_schema_create_all(self, engine):
+        """A hook which should generate the model schema using create_all().
+
+        This hook is called within the scope of creating the database
+        assuming BUILD_WITH_MIGRATIONS is False.
+
+        """
+
+
+class GeneratesSchemaFromMigrations(GeneratesSchema):
+    """Mixin defining a fixture as generating a schema using migrations.
+
+    This is a "capability" mixin that works in conjunction with classes
+    that include BaseDbFixture as a base.
+
+    """
+
+    _BUILD_WITH_MIGRATIONS = True
+
+    def generate_schema_migrations(self, engine):
+        """A hook which should generate the model schema using migrations.
+
+
+        This hook is called within the scope of creating the database
+        assuming BUILD_WITH_MIGRATIONS is True.
+
+        """
+
+
+class ResetsData(object):
+    """Mixin defining a fixture that resets schema data without dropping."""
+
+    _DROP_SCHEMA_PER_TEST = False
+
+    def setup_for_reset(self, engine, enginefacade):
+        """"Perform setup that may be needed before the test runs."""
+
+    def reset_schema_data(self, engine, enginefacade):
+        """Reset the data in the schema."""
+
+
+class DeletesFromSchema(ResetsData):
+    """Mixin defining a fixture that can delete from all tables in place.
+
+    When DeletesFromSchema is present in a fixture,
+    _DROP_SCHEMA_PER_TEST is now False; this means that the
+    "teardown" flag of provision.SchemaResource will be False, which
+    prevents SchemaResource from dropping all objects within the schema
+    after each test.
+
+    This is a "capability" mixin that works in conjunction with classes
+    that include BaseDbFixture as a base.
+
+    """
+
+    def reset_schema_data(self, engine, facade):
+        self.delete_from_schema(engine)
+
+    def delete_from_schema(self, engine):
+        """A hook which should delete all data from an existing schema.
+
+        Should *not* drop any objects, just remove data from tables
+        that needs to be reset between tests.
+        """
+
+
+class RollsBackTransaction(ResetsData):
+    """Fixture class that maintains a database transaction per test.
+
+    """
+
+    def setup_for_reset(self, engine, facade):
+        conn = engine.connect()
+        engine = utils.NonCommittingEngine(conn)
+        self._reset_engine = enginefacade._TestTransactionFactory.apply_engine(
+            engine, facade)
+
+    def reset_schema_data(self, engine, facade):
+        self._reset_engine()
+        engine._dispose()
+
+
+class SimpleDbFixture(BaseDbFixture):
+    """Fixture which provides an engine from a fixed URL.
+
+    The SimpleDbFixture is generally appropriate only for a SQLite memory
+    database, as this database is naturally isolated from other processes and
+    does not require management of schemas.   For tests that need to
+    run specifically against MySQL or Postgresql, the OpportunisticDbFixture
+    is more appropriate.
+
+    The database connection information itself comes from the provisoning
+    system, matching the desired driver (typically sqlite) to the default URL
+    that provisioning provides for this driver (in the case of sqlite, it's
+    the SQLite memory URL, e.g. sqlite://.  For MySQL and Postgresql, it's
+    the familiar "openstack_citest" URL on localhost).
+
+    There are a variety of create/drop schemes that can take place:
+
+    * The default is to procure a database connection on setup,
+      and at teardown, an instruction is issued to "drop" all
+      objects in the schema (e.g. tables, indexes).  The SQLAlchemy
+      engine itself remains referenced at the class level for subsequent
+      re-use.
+
+    * When the GeneratesSchema or GeneratesSchemaFromMigrations mixins
+      are implemented, the appropriate generate_schema method is also
+      called when the fixture is set up, by default this is per test.
+
+    * When the DeletesFromSchema mixin is implemented, the generate_schema
+      method is now only called **once**, and the "drop all objects"
+      system is replaced with the delete_from_schema method.   This
+      allows the same database to remain set up with all schema objects
+      intact, so that expensive migrations need not be run on every test.
+
+    * The fixture does **not** dispose the engine at the end of a test.
+      It is assumed the same engine will be re-used many times across
+      many tests.  The AdHocDbFixture extends this one to provide
+      engine.dispose() at the end of a test.
+
+    This fixture is intended to work without needing a reference to
+    the test itself, and therefore cannot take advantage of the
+    OptimisingTestSuite.
+
+    """
+
+    _dependency_resources = {}
+
+    def _get_provisioned_db(self):
+        return self._dependency_resources["_db_%s" % self.ident]
+
+    def _generate_database_resource(self, _enginefacade):
+        return provision.DatabaseResource(self.driver, _enginefacade)
+
+    def _setUp(self):
+        super(SimpleDbFixture, self)._setUp()
+
+        cls = self.__class__
+
+        if "_db_%s" % self.ident not in cls._dependency_resources:
+
+            resources = self._get_resources()
+
+            # initialize resources the same way that testresources does.
+            for name, resource in resources:
+                cls._dependency_resources[name] = resource.getResource()
+
+        provisioned_db = self._get_provisioned_db()
+
+        if not self._DROP_SCHEMA_PER_TEST:
+            self.setup_for_reset(
+                provisioned_db.engine, provisioned_db.enginefacade)
+
+        self.useFixture(ReplaceEngineFacadeFixture(
+            self.get_per_test_enginefacade(),
+            provisioned_db.enginefacade
+            ))
+
+        if not self._DROP_SCHEMA_PER_TEST:
+            self.addCleanup(
+                self.reset_schema_data,
+                provisioned_db.engine, provisioned_db.enginefacade)
+
+        self.addCleanup(self._cleanup)
+
+    def _teardown_resources(self):
+        for name, resource in self._get_resources():
+            dep = self._dependency_resources.pop(name)
+            resource.finishedWith(dep)
+
+    def _cleanup(self):
+        pass
+
+
+class AdHocDbFixture(SimpleDbFixture):
+    """"Fixture which creates and disposes a database engine per test.
+
+    Also allows a specific URL to be passed, meaning the fixture can
+    be hardcoded to a specific SQLite file.
+
+    For a SQLite, this fixture will create the named database upon setup
+    and tear it down upon teardown.   For other databases, the
+    database is assumed to exist already and will remain after teardown.
+
+    """
+    def __init__(self, url=None):
+        if url:
+            self.url = provision.sa_url.make_url(str(url))
+            driver = self.url.get_backend_name()
+        else:
+            driver = None
+            self.url = None
+
+        BaseDbFixture.__init__(
+            self, driver=driver,
+            ident=provision._random_ident())
+        self.url = url
+
+    def _generate_database_resource(self, _enginefacade):
+        return provision.DatabaseResource(
+            self.driver, _enginefacade, ad_hoc_url=self.url)
+
+    def _cleanup(self):
+        self._teardown_resources()
+
+
+class OpportunisticDbFixture(BaseDbFixture):
+    """Fixture which uses testresources fully for optimised runs.
+
+    This fixture relies upon the use of the OpportunisticDBTestMixin to supply
+    a test.resources attribute, and also works much more effectively when
+    combined the testresources.OptimisingTestSuite.   The
+    optimize_db_test_loader() function should be used at the module and package
+    levels to optimize database provisioning across many tests.
+
+    """
+    def __init__(self, test, driver=None, ident=None):
+        super(OpportunisticDbFixture, self).__init__(
+            driver=driver, ident=ident)
+        self.test = test
+
+    def _get_provisioned_db(self):
+        return getattr(self.test, "_db_%s" % self.ident)
+
+    def _generate_database_resource(self, _enginefacade):
+        return provision.DatabaseResource(
+            self.driver, _enginefacade, provision_new_database=True)
+
+    def _setUp(self):
+        super(OpportunisticDbFixture, self)._setUp()
+
+        if not self._has_db_resource():
+            return
+
+        provisioned_db = self._get_provisioned_db()
+
+        if not self._DROP_SCHEMA_PER_TEST:
+            self.setup_for_reset(
+                provisioned_db.engine, provisioned_db.enginefacade)
+
+        self.useFixture(ReplaceEngineFacadeFixture(
+            self.get_per_test_enginefacade(),
+            provisioned_db.enginefacade
+            ))
+
+        if not self._DROP_SCHEMA_PER_TEST:
+            self.addCleanup(
+                self.reset_schema_data,
+                provisioned_db.engine, provisioned_db.enginefacade)
+
+
+class OpportunisticDBTestMixin(object):
+    """Test mixin that integrates the test suite with testresources.
+
+    There are three goals to this system:
+
+    1. Allow creation of "stub" test suites that will run all the tests    in a
+       parent suite against a specific    kind of database (e.g. Mysql,
+       Postgresql), where the entire suite will be skipped if that    target
+       kind of database is not available to the suite.
+
+    2. provide a test with a process-local, anonymously named schema within a
+       target database, so that the test can run concurrently with other tests
+       without conflicting data
+
+    3. provide compatibility with the testresources.OptimisingTestSuite, which
+       organizes TestCase instances ahead of time into groups that all
+       make use of the same type of database, setting up and tearing down
+       a database schema once for the scope of any number of tests within.
+       This technique is essential when testing against a non-SQLite database
+       because building of a schema is expensive, and also is most ideally
+       accomplished using the applications schema migration which are
+       even more vastly slow than a straight create_all().
+
+    This mixin provides the .resources attribute required by testresources when
+    using the OptimisingTestSuite.The .resources attribute then provides a
+    collection of testresources.TestResourceManager objects, which are defined
+    here in oslo_db.sqlalchemy.provision.   These objects know how to find
+    available database backends, build up temporary databases, and invoke
+    schema generation and teardown instructions.   The actual "build the schema
+    objects" part of the equation, and optionally a "delete from all the
+    tables" step, is provided by the implementing application itself.
+
+
+    """
+    SKIP_ON_UNAVAILABLE_DB = True
+
+    FIXTURE = OpportunisticDbFixture
+
+    _collected_resources = None
+    _instantiated_fixtures = None
+
+    @property
+    def resources(self):
+        """Provide a collection of TestResourceManager objects.
+
+        The collection here is memoized, both at the level of the test
+        case itself, as well as in the fixture object(s) which provide
+        those resources.
+
+        """
+
+        if self._collected_resources is not None:
+            return self._collected_resources
+
+        fixtures = self._instantiate_fixtures()
+        self._collected_resources = []
+        for fixture in fixtures:
+            self._collected_resources.extend(fixture._get_resources())
+        return self._collected_resources
+
+    def setUp(self):
+        self._setup_fixtures()
+        super(OpportunisticDBTestMixin, self).setUp()
+
+    def _get_default_provisioned_db(self):
+        return self._db_default
+
+    def _instantiate_fixtures(self):
+        if self._instantiated_fixtures:
+            return self._instantiated_fixtures
+
+        self._instantiated_fixtures = utils.to_list(self.generate_fixtures())
+        return self._instantiated_fixtures
+
+    def generate_fixtures(self):
+        return self.FIXTURE(test=self)
+
+    def _setup_fixtures(self):
+        testresources.setUpResources(
+            self, self.resources, testresources._get_result())
+        self.addCleanup(
+            testresources.tearDownResources,
+            self, self.resources, testresources._get_result()
+        )
+
+        fixtures = self._instantiate_fixtures()
+        for fixture in fixtures:
+            self.useFixture(fixture)
+
+            if not fixture._has_db_resource():
+                msg = fixture._get_db_resource_not_available_reason()
+                if self.SKIP_ON_UNAVAILABLE_DB:
+                    self.skip(msg)
+                else:
+                    self.fail(msg)
+
+
+class MySQLOpportunisticFixture(OpportunisticDbFixture):
+    DRIVER = 'mysql'
+
+
+class PostgresqlOpportunisticFixture(OpportunisticDbFixture):
+    DRIVER = 'postgresql'
diff --git a/oslo_db/sqlalchemy/test_migrations.py b/oslo_db/sqlalchemy/test_migrations.py
index 524a339..549654c 100644
--- a/oslo_db/sqlalchemy/test_migrations.py
+++ b/oslo_db/sqlalchemy/test_migrations.py
@@ -32,6 +32,7 @@ import sqlalchemy.types as types
 
 from oslo_db._i18n import _LE
 from oslo_db import exception as exc
+from oslo_db.sqlalchemy import provision
 from oslo_db.sqlalchemy import utils
 
 LOG = logging.getLogger(__name__)
@@ -595,7 +596,9 @@ class ModelsMigrationsSync(object):
                           ' for running of this test: %s' % e)
 
         # drop all tables after a test run
-        self.addCleanup(functools.partial(self.db.backend.drop_all_objects,
+        backend = provision.Backend.backend_for_database_type(
+            self.get_engine().name)
+        self.addCleanup(functools.partial(backend.drop_all_objects,
                                           self.get_engine()))
 
         # run migration scripts
diff --git a/oslo_db/tests/sqlalchemy/base.py b/oslo_db/tests/sqlalchemy/base.py
new file mode 100644
index 0000000..a23f249
--- /dev/null
+++ b/oslo_db/tests/sqlalchemy/base.py
@@ -0,0 +1,43 @@
+# Copyright (c) 2016 Openstack Foundation
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslo_db.sqlalchemy import enginefacade
+from oslo_db.sqlalchemy.test_base import backend_specific  # noqa
+from oslo_db.sqlalchemy import test_fixtures as db_fixtures
+from oslotest import base as test_base
+
+
+@enginefacade.transaction_context_provider
+class Context(object):
+    pass
+
+context = Context()
+
+
+class DbTestCase(db_fixtures.OpportunisticDBTestMixin, test_base.BaseTestCase):
+
+    def setUp(self):
+        super(DbTestCase, self).setUp()
+
+        self.engine = enginefacade.writer.get_engine()
+        self.sessionmaker = enginefacade.writer.get_sessionmaker()
+
+
+class MySQLOpportunisticTestCase(DbTestCase):
+    FIXTURE = db_fixtures.MySQLOpportunisticFixture
+
+
+class PostgreSQLOpportunisticTestCase(DbTestCase):
+    FIXTURE = db_fixtures.PostgresqlOpportunisticFixture
diff --git a/oslo_db/tests/sqlalchemy/test_async_eventlet.py b/oslo_db/tests/sqlalchemy/test_async_eventlet.py
index 58e4787..34d1f32 100644
--- a/oslo_db/tests/sqlalchemy/test_async_eventlet.py
+++ b/oslo_db/tests/sqlalchemy/test_async_eventlet.py
@@ -24,8 +24,8 @@ from sqlalchemy.ext import declarative as sa_decl
 
 from oslo_db import exception as db_exc
 from oslo_db.sqlalchemy import models
-from oslo_db.sqlalchemy import test_base
 from oslo_db import tests
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 class EventletTestMixin(object):
diff --git a/oslo_db/tests/sqlalchemy/test_enginefacade.py b/oslo_db/tests/sqlalchemy/test_enginefacade.py
index 517b7f9..9d84c1a 100644
--- a/oslo_db/tests/sqlalchemy/test_enginefacade.py
+++ b/oslo_db/tests/sqlalchemy/test_enginefacade.py
@@ -33,7 +33,7 @@ from oslo_db import options
 from oslo_db.sqlalchemy import enginefacade
 from oslo_db.sqlalchemy import engines as oslo_engines
 from oslo_db.sqlalchemy import orm
-from oslo_db.sqlalchemy import test_base
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 enginefacade.transaction_context_provider(oslo_context.RequestContext)
diff --git a/oslo_db/tests/sqlalchemy/test_exc_filters.py b/oslo_db/tests/sqlalchemy/test_exc_filters.py
index e3a3a3a..a45214d 100644
--- a/oslo_db/tests/sqlalchemy/test_exc_filters.py
+++ b/oslo_db/tests/sqlalchemy/test_exc_filters.py
@@ -30,7 +30,7 @@ from sqlalchemy.orm import mapper
 from oslo_db import exception
 from oslo_db.sqlalchemy import engines
 from oslo_db.sqlalchemy import exc_filters
-from oslo_db.sqlalchemy import test_base
+from oslo_db.tests.sqlalchemy import base as test_base
 from oslo_db.tests import utils as test_utils
 
 _TABLE_NAME = '__tmp__test__tmp__'
diff --git a/oslo_db/tests/sqlalchemy/test_fixtures.py b/oslo_db/tests/sqlalchemy/test_fixtures.py
index 5d63d69..08723b4 100644
--- a/oslo_db/tests/sqlalchemy/test_fixtures.py
+++ b/oslo_db/tests/sqlalchemy/test_fixtures.py
@@ -11,9 +11,12 @@
 #    under the License.
 
 import mock
+import testresources
 
+from oslo_db.sqlalchemy import enginefacade
 from oslo_db.sqlalchemy import provision
-from oslo_db.sqlalchemy import test_base
+from oslo_db.sqlalchemy import test_base as legacy_test_base
+from oslo_db.sqlalchemy import test_fixtures
 from oslotest import base as oslo_test_base
 
 
@@ -21,10 +24,12 @@ class BackendSkipTest(oslo_test_base.BaseTestCase):
 
     def test_skip_no_dbapi(self):
 
-        class FakeDatabaseOpportunisticFixture(test_base.DbFixture):
+        class FakeDatabaseOpportunisticFixture(
+                test_fixtures.OpportunisticDbFixture):
             DRIVER = 'postgresql'
 
-        class SomeTest(test_base.DbTestCase):
+        class SomeTest(test_fixtures.OpportunisticDBTestMixin,
+                       oslo_test_base.BaseTestCase):
             FIXTURE = FakeDatabaseOpportunisticFixture
 
             def runTest(self):
@@ -61,10 +66,79 @@ class BackendSkipTest(oslo_test_base.BaseTestCase):
 
     def test_skip_no_such_backend(self):
 
-        class FakeDatabaseOpportunisticFixture(test_base.DbFixture):
+        class FakeDatabaseOpportunisticFixture(
+                test_fixtures.OpportunisticDbFixture):
             DRIVER = 'postgresql+nosuchdbapi'
 
-        class SomeTest(test_base.DbTestCase):
+        class SomeTest(test_fixtures.OpportunisticDBTestMixin,
+                       oslo_test_base.BaseTestCase):
+
+            FIXTURE = FakeDatabaseOpportunisticFixture
+
+            def runTest(self):
+                pass
+
+        st = SomeTest()
+
+        ex = self.assertRaises(
+            self.skipException,
+            st.setUp
+        )
+
+        self.assertEqual(
+            "Backend 'postgresql+nosuchdbapi' is unavailable: No such backend",
+            str(ex)
+        )
+
+    def test_skip_no_dbapi_legacy(self):
+
+        class FakeDatabaseOpportunisticFixture(
+                legacy_test_base.DbFixture):
+            DRIVER = 'postgresql'
+
+        class SomeTest(legacy_test_base.DbTestCase):
+            FIXTURE = FakeDatabaseOpportunisticFixture
+
+            def runTest(self):
+                pass
+
+        st = SomeTest()
+
+        # patch in replacement lookup dictionaries to avoid
+        # leaking from/to other tests
+        with mock.patch(
+                "oslo_db.sqlalchemy.provision."
+                "Backend.backends_by_database_type", {
+                    "postgresql":
+                    provision.Backend("postgresql", "postgresql://")}):
+            st._database_resources = {}
+            st._db_not_available = {}
+            st._schema_resources = {}
+
+            with mock.patch(
+                    "sqlalchemy.create_engine",
+                    mock.Mock(side_effect=ImportError())):
+
+                self.assertEqual([], st.resources)
+
+                ex = self.assertRaises(
+                    self.skipException,
+                    st.setUp
+                )
+
+        self.assertEqual(
+            "Backend 'postgresql' is unavailable: No DBAPI installed",
+            str(ex)
+        )
+
+    def test_skip_no_such_backend_legacy(self):
+
+        class FakeDatabaseOpportunisticFixture(
+                legacy_test_base.DbFixture):
+            DRIVER = 'postgresql+nosuchdbapi'
+
+        class SomeTest(legacy_test_base.DbTestCase):
+
             FIXTURE = FakeDatabaseOpportunisticFixture
 
             def runTest(self):
@@ -81,3 +155,44 @@ class BackendSkipTest(oslo_test_base.BaseTestCase):
             "Backend 'postgresql+nosuchdbapi' is unavailable: No such backend",
             str(ex)
         )
+
+
+class EnginefacadeIntegrationTest(oslo_test_base.BaseTestCase):
+    def test_db_fixture(self):
+        normal_mgr = enginefacade.transaction_context()
+        normal_mgr.configure(
+            connection="sqlite://",
+            sqlite_fk=True,
+            mysql_sql_mode="FOOBAR",
+            max_overflow=38
+        )
+
+        class MyFixture(test_fixtures.OpportunisticDbFixture):
+            def get_enginefacade(self):
+                return normal_mgr
+
+        test = mock.Mock(SCHEMA_SCOPE=None)
+        fixture = MyFixture(test=test)
+        resources = fixture._get_resources()
+
+        testresources.setUpResources(test, resources, None)
+        self.addCleanup(
+            testresources.tearDownResources,
+            test, resources, None
+        )
+        fixture.setUp()
+        self.addCleanup(fixture.cleanUp)
+
+        self.assertTrue(normal_mgr._factory._started)
+
+        test.engine = normal_mgr.writer.get_engine()
+        self.assertEqual("sqlite://", str(test.engine.url))
+        self.assertIs(test.engine, normal_mgr._factory._writer_engine)
+        engine_args = normal_mgr._factory._engine_args_for_conf(None)
+        self.assertTrue(engine_args['sqlite_fk'])
+        self.assertEqual("FOOBAR", engine_args["mysql_sql_mode"])
+        self.assertEqual(38, engine_args["max_overflow"])
+
+        fixture.cleanUp()
+        fixture._clear_cleanups()  # so the real cleanUp works
+        self.assertFalse(normal_mgr._factory._started)
diff --git a/oslo_db/tests/sqlalchemy/test_migration_common.py b/oslo_db/tests/sqlalchemy/test_migration_common.py
index 9041b90..c8203ac 100644
--- a/oslo_db/tests/sqlalchemy/test_migration_common.py
+++ b/oslo_db/tests/sqlalchemy/test_migration_common.py
@@ -24,7 +24,7 @@ import sqlalchemy
 
 from oslo_db import exception as db_exception
 from oslo_db.sqlalchemy import migration
-from oslo_db.sqlalchemy import test_base
+from oslo_db.tests.sqlalchemy import base as test_base
 from oslo_db.tests import utils as test_utils
 
 
diff --git a/oslo_db/tests/sqlalchemy/test_migrations.py b/oslo_db/tests/sqlalchemy/test_migrations.py
index 7a17fb4..d42812d 100644
--- a/oslo_db/tests/sqlalchemy/test_migrations.py
+++ b/oslo_db/tests/sqlalchemy/test_migrations.py
@@ -23,8 +23,8 @@ import sqlalchemy as sa
 import sqlalchemy.ext.declarative as sa_decl
 
 from oslo_db import exception as exc
-from oslo_db.sqlalchemy import test_base
 from oslo_db.sqlalchemy import test_migrations as migrate
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 class TestWalkVersions(test.BaseTestCase, migrate.WalkVersionsMixin):
diff --git a/oslo_db/tests/sqlalchemy/test_models.py b/oslo_db/tests/sqlalchemy/test_models.py
index 1699bbc..60e8c55 100644
--- a/oslo_db/tests/sqlalchemy/test_models.py
+++ b/oslo_db/tests/sqlalchemy/test_models.py
@@ -21,7 +21,7 @@ from sqlalchemy import Integer, String
 from sqlalchemy.ext.declarative import declarative_base
 
 from oslo_db.sqlalchemy import models
-from oslo_db.sqlalchemy import test_base
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 BASE = declarative_base()
diff --git a/oslo_db/tests/sqlalchemy/test_provision.py b/oslo_db/tests/sqlalchemy/test_provision.py
index 53d2303..8f931bd 100644
--- a/oslo_db/tests/sqlalchemy/test_provision.py
+++ b/oslo_db/tests/sqlalchemy/test_provision.py
@@ -11,6 +11,8 @@
 #    under the License.
 
 import mock
+import os
+
 from oslotest import base as oslo_test_base
 from sqlalchemy import exc as sa_exc
 from sqlalchemy import inspect
@@ -18,8 +20,11 @@ from sqlalchemy import schema
 from sqlalchemy import types
 
 from oslo_db import exception
+from oslo_db.sqlalchemy import enginefacade
 from oslo_db.sqlalchemy import provision
-from oslo_db.sqlalchemy import test_base
+from oslo_db.sqlalchemy import test_fixtures
+from oslo_db.sqlalchemy import utils
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 class DropAllObjectsTest(test_base.DbTestCase):
@@ -66,7 +71,8 @@ class DropAllObjectsTest(test_base.DbTestCase):
             set(insp.get_table_names())
         )
 
-        self.db.backend.drop_all_objects(self.engine)
+        self._get_default_provisioned_db().\
+            backend.drop_all_objects(self.engine)
 
         insp = inspect(self.engine)
         self.assertEqual(
@@ -167,16 +173,18 @@ class RetainSchemaTest(oslo_test_base.BaseTestCase):
 
     def _run_test(self):
         try:
-            database_resource = provision.DatabaseResource(self.DRIVER)
+            database_resource = provision.DatabaseResource(
+                self.DRIVER, provision_new_database=True)
         except exception.BackendNotAvailable:
             self.skip("database not available")
 
         schema_resource = provision.SchemaResource(
             database_resource, self._gen_schema)
-        transaction_resource = provision.TransactionResource(
-            database_resource, schema_resource)
 
-        engine = transaction_resource.getResource()
+        schema = schema_resource.getResource()
+
+        conn = schema.database.engine.connect()
+        engine = utils.NonCommittingEngine(conn)
 
         with engine.connect() as conn:
             rows = conn.execute(self.test_table.select())
@@ -202,7 +210,8 @@ class RetainSchemaTest(oslo_test_base.BaseTestCase):
             rows = conn.execute(self.test_table.select())
             self.assertEqual([(2, 3)], rows.fetchall())
 
-        transaction_resource.finishedWith(engine)
+        engine._dispose()
+        schema_resource.finishedWith(schema)
 
 
 class MySQLRetainSchemaTest(RetainSchemaTest):
@@ -211,3 +220,45 @@ class MySQLRetainSchemaTest(RetainSchemaTest):
 
 class PostgresqlRetainSchemaTest(RetainSchemaTest):
     DRIVER = "postgresql"
+
+
+class AdHocURLTest(oslo_test_base.BaseTestCase):
+    def test_sqlite_setup_teardown(self):
+
+        fixture = test_fixtures.AdHocDbFixture("sqlite:///foo.db")
+
+        fixture.setUp()
+
+        self.assertEqual(
+            str(enginefacade._context_manager._factory._writer_engine.url),
+            "sqlite:///foo.db"
+            )
+
+        self.assertTrue(os.path.exists("foo.db"))
+        fixture.cleanUp()
+
+        self.assertFalse(os.path.exists("foo.db"))
+
+    def test_mysql_setup_teardown(self):
+        try:
+            mysql_backend = provision.Backend.backend_for_database_type(
+                "mysql")
+        except exception.BackendNotAvailable:
+            self.skip("mysql backend not available")
+
+        mysql_backend.create_named_database("adhoc_test")
+        self.addCleanup(
+            mysql_backend.drop_named_database, "adhoc_test"
+        )
+        url = str(mysql_backend.provisioned_database_url("adhoc_test"))
+
+        fixture = test_fixtures.AdHocDbFixture(url)
+
+        fixture.setUp()
+
+        self.assertEqual(
+            str(enginefacade._context_manager._factory._writer_engine.url),
+            url
+        )
+
+        fixture.cleanUp()
diff --git a/oslo_db/tests/sqlalchemy/test_sqlalchemy.py b/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
index 9f1e655..a37cdc6 100644
--- a/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
+++ b/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
@@ -33,10 +33,11 @@ from sqlalchemy.ext.declarative import declarative_base
 
 from oslo_db import exception
 from oslo_db import options as db_options
+from oslo_db.sqlalchemy import enginefacade
 from oslo_db.sqlalchemy import engines
 from oslo_db.sqlalchemy import models
 from oslo_db.sqlalchemy import session
-from oslo_db.sqlalchemy import test_base
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 BASE = declarative_base()
@@ -65,8 +66,8 @@ class RegexpFilterTestCase(test_base.DbTestCase):
         self.addCleanup(test_table.drop)
 
     def _test_regexp_filter(self, regexp, expected):
-        _session = self.sessionmaker()
-        with _session.begin():
+        with enginefacade.writer.using(test_base.context):
+            _session = test_base.context.session
             for i in ['10', '20', u'♥']:
                 tbl = RegexpTable()
                 tbl.update({'bar': i})
diff --git a/oslo_db/tests/sqlalchemy/test_types.py b/oslo_db/tests/sqlalchemy/test_types.py
index 4636c49..6103ce3 100644
--- a/oslo_db/tests/sqlalchemy/test_types.py
+++ b/oslo_db/tests/sqlalchemy/test_types.py
@@ -18,8 +18,8 @@ from sqlalchemy.ext.declarative import declarative_base
 
 from oslo_db import exception as db_exc
 from oslo_db.sqlalchemy import models
-from oslo_db.sqlalchemy import test_base
 from oslo_db.sqlalchemy import types
+from oslo_db.tests.sqlalchemy import base as test_base
 
 
 BASE = declarative_base()
diff --git a/oslo_db/tests/sqlalchemy/test_update_match.py b/oslo_db/tests/sqlalchemy/test_update_match.py
index ecc7af7..c876bf3 100644
--- a/oslo_db/tests/sqlalchemy/test_update_match.py
+++ b/oslo_db/tests/sqlalchemy/test_update_match.py
@@ -17,8 +17,8 @@ from sqlalchemy import schema
 from sqlalchemy import sql
 from sqlalchemy import types as sqltypes
 
-from oslo_db.sqlalchemy import test_base
 from oslo_db.sqlalchemy import update_match
+from oslo_db.tests.sqlalchemy import base as test_base
 
 Base = declarative.declarative_base()
 
diff --git a/oslo_db/tests/sqlalchemy/test_utils.py b/oslo_db/tests/sqlalchemy/test_utils.py
index 2e4b865..906321c 100644
--- a/oslo_db/tests/sqlalchemy/test_utils.py
+++ b/oslo_db/tests/sqlalchemy/test_utils.py
@@ -42,8 +42,8 @@ from oslo_db.sqlalchemy.compat import utils as compat_utils
 from oslo_db.sqlalchemy import models
 from oslo_db.sqlalchemy import provision
 from oslo_db.sqlalchemy import session
-from oslo_db.sqlalchemy import test_base as db_test_base
 from oslo_db.sqlalchemy import utils
+from oslo_db.tests.sqlalchemy import base as db_test_base
 from oslo_db.tests import utils as test_utils
 
 
diff --git a/releasenotes/notes/new-db-fixtures-58223e3926122413.yaml b/releasenotes/notes/new-db-fixtures-58223e3926122413.yaml
new file mode 100644
index 0000000..474f505
--- /dev/null
+++ b/releasenotes/notes/new-db-fixtures-58223e3926122413.yaml
@@ -0,0 +1,5 @@
+---
+deprecations:
+  - base test classes from ``oslo_db.sqlalchemy.test_base`` are deprecated in
+    favor of new fixtures introduced in ``oslo_db.sqlalchemy.test_fixtures``
+    module