Use memory mode for sqlite in db test

Config option sqlite_db is deprecated in
0a1bae9859079fb21a03716be947c5f1da6db0a2, and deprecate
argument sqlite_db in method set_defaults in
https://review.openstack.org/#/c/350945/, should use config option
connection instead. For Ironic, we test database with sqlite in memory
mode [1] as below:
  CONF.set_default('connection', "sqlite://", group='database')
and don't use config option sqlite_db, so remove unused code.

[1]http://docs.sqlalchemy.org/en/rel_1_0/core/engines.html#sqlite

Change-Id: I52b4e31d112283b538275d818c6151e62d1ef78d

ironic/tests/unit/db/base.py

@@ -15,14 +15,10 @@
 
 """Ironic DB test base class."""
 
-import os
-import shutil
-
 import fixtures
 from oslo_config import cfg
 from oslo_db.sqlalchemy import enginefacade
 
-from ironic.common import paths
 from ironic.db import api as dbapi
 from ironic.db.sqlalchemy import migration
 from ironic.db.sqlalchemy import models
@@ -36,32 +32,17 @@ _DB_CACHE = None
 
 class Database(fixtures.Fixture):
 
-    def __init__(self, engine, db_migrate, sql_connection,
-                 sqlite_db, sqlite_clean_db):
+    def __init__(self, engine, db_migrate, sql_connection):
         self.sql_connection = sql_connection
-        self.sqlite_db = sqlite_db
-        self.sqlite_clean_db = sqlite_clean_db
 
         self.engine = engine
         self.engine.dispose()
         conn = self.engine.connect()
-        if sql_connection == "sqlite://":
-            self.setup_sqlite(db_migrate)
-        elif sql_connection.startswith('sqlite:///'):
-            testdb = paths.state_path_rel(sqlite_db)
-            if os.path.exists(testdb):
-                return
-            self.setup_sqlite(db_migrate)
-        else:
-            db_migrate.upgrade('head')
+        self.setup_sqlite(db_migrate)
+
         self.post_migrations()
-        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)
+        self._DB = "".join(line for line in conn.connection.iterdump())
+        self.engine.dispose()
 
     def setup_sqlite(self, db_migrate):
         if db_migrate.version():
@@ -72,14 +53,9 @@ class Database(fixtures.Fixture):
     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))
-            self.addCleanup(os.unlink, self.sqlite_db)
+        conn = self.engine.connect()
+        conn.connection.executescript(self._DB)
+        self.addCleanup(self.engine.dispose)
 
     def post_migrations(self):
         """Any addition steps that are needed outside of the migrations."""
@@ -96,7 +72,5 @@ class DbTestCase(base.TestCase):
         if not _DB_CACHE:
             engine = enginefacade.get_legacy_facade().get_engine()
             _DB_CACHE = Database(engine, migration,
-                                 sql_connection=CONF.database.connection,
-                                 sqlite_db=CONF.database.sqlite_db,
-                                 sqlite_clean_db='clean.sqlite')
+                                 sql_connection=CONF.database.connection)
         self.useFixture(_DB_CACHE)