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

1 files changed, 34 insertions, 0 deletions

diff --git a/nova/tests/unit/test_fixtures.py b/nova/tests/unit/test_fixtures.py
index bf1671f84e..82407ca07e 100644
--- a/nova/tests/unit/test_fixtures.py
+++ b/nova/tests/unit/test_fixtures.py
@@ -21,6 +21,7 @@ import fixtures as fx
 from oslo.config import cfg
 import testtools
 
+from nova.db.sqlalchemy import api as session
 from nova.tests.unit import conf_fixture
 from nova.tests import fixtures
 
@@ -145,3 +146,36 @@ class TestTimeout(testtools.TestCase):
         self.assertEqual(timeout.test_timeout, 10)
         timeout = fixtures.Timeout("10", 2)
         self.assertEqual(timeout.test_timeout, 20)
+
+
+class TestDatabaseFixture(testtools.TestCase):
+    def test_fixture_reset(self):
+        # because this sets up reasonable db connection strings
+        self.useFixture(conf_fixture.ConfFixture())
+        self.useFixture(fixtures.Database())
+        engine = session.get_engine()
+        conn = engine.connect()
+        result = conn.execute("select * from instance_types")
+        rows = result.fetchall()
+        self.assertEqual(len(rows), 5, "Rows %s" % rows)
+
+        # insert a 6th instance type, column 5 below is an int id
+        # which has a constraint on it, so if new standard instance
+        # types are added you have to bump it.
+        conn.execute("insert into instance_types VALUES "
+                     "(NULL, NULL, NULL, 't1.test', 6, 4096, 2, 0, NULL, '87'"
+                     ", 1.0, 40, 0, 0, 1, 0)")
+        result = conn.execute("select * from instance_types")
+        rows = result.fetchall()
+        self.assertEqual(len(rows), 6, "Rows %s" % rows)
+
+        # reset by invoking the fixture again
+        #
+        # NOTE(sdague): it's important to reestablish the db
+        # connection because otherwise we have a reference to the old
+        # in mem db.
+        self.useFixture(fixtures.Database())
+        conn = engine.connect()
+        result = conn.execute("select * from instance_types")
+        rows = result.fetchall()
+        self.assertEqual(len(rows), 5, "Rows %s" % rows)