Fix for sqlite support on migrations

SQLite support was broken by a migration which needed an ALTER TABLE
on a constraint of test_runs as ALTER TABLE support on SQLite is
very shallow.
Alembic developers suggest using batch_alter_table method for these
situations http://alembic.readthedocs.org/en/latest/batch.html.

Besides the batch_alter_table change a forced drop_index is needed
for sqlite provider as index are created on a global namespace and
it couldn't create a new temp table with an index with the same_
name.

Change-Id: I287bc710369325bc626b62aea7eb6d0f46f8314a

subunit2sql/migrations/env.py

@@ -61,6 +61,7 @@ def run_migrations_offline():
     else:
         kwargs['url'] = config.get_main_option("sqlalchemy.url")
     kwargs['target_metadata'] = target_metadata
+    kwargs['render_as_batch'] = True
     context.configure(**kwargs)
 
     with context.begin_transaction():
@@ -80,7 +81,9 @@ def run_migrations_online():
     connection = engine.connect()
     facade._session_maker.configure(bind=connection)
 
-    context.configure(connection=connection, target_metadata=target_metadata)
+    context.configure(connection=connection,
+                      target_metadata=target_metadata,
+                      render_as_batch=True)
 
     try:
         with context.begin_transaction():

subunit2sql/migrations/versions/13d819bbb0ff_create_missing_indexes.py

@@ -43,6 +43,19 @@ def upgrade():
     if ('ix_test_id' not in test_indx_names and
         'test_id' not in test_indx_columns):
         op.create_index('ix_test_id', 'tests', ['test_id'], mysql_length=30)
+
+    # remove auto created indexes (sqlite only)
+    # note the name is with test_runs not test_run
+    if migration_context.dialect.name == 'sqlite':
+        if 'ix_test_runs_test_id' in test_run_indx_names:
+            op.drop_index('ix_test_runs_test_id', 'test_runs')
+        if 'ix_test_runs_run_id' in test_run_indx_names:
+            op.drop_index('ix_test_runs_run_id', 'test_runs')
+
+    with op.batch_alter_table('test_runs') as batch_op:
+        batch_op.create_unique_constraint('uq_test_runs',
+                                          ['test_id', 'run_id'])
+
     if ('ix_test_run_test_id' not in test_run_indx_names and
         'test_id' not in test_run_indx_columns):
         op.create_index('ix_test_run_test_id', 'test_runs', ['test_id'])
@@ -50,9 +63,6 @@ def upgrade():
         'run_id' not in test_run_indx_columns):
         op.create_index('ix_test_run_run_id', 'test_runs', ['run_id'])
 
-    op.create_unique_constraint('uq_test_runs', 'test_runs',
-                                ['test_id', 'run_id'])
-
 
 def downgrade():
     op.drop_constraint('uq_test_runs', 'test_runs')

subunit2sql/tests/db_test_utils.py

@@ -13,6 +13,7 @@
 # under the License.
 
 import os
+import tempfile
 
 from alembic import command
 from alembic import config as alembic_config
@@ -22,6 +23,7 @@ import sqlalchemy
 from subunit2sql.db import api as session
 
 CONF = cfg.CONF
+SQLITE_TEST_DATABASE_PATH = tempfile.mkstemp('subunit2sql.db')[1]
 
 script_location = os.path.join(os.path.dirname(os.path.dirname(
     os.path.abspath(__file__))), 'migrations')
@@ -41,6 +43,9 @@ def get_connect_string(backend,
     elif backend == "postgres":
         backend = "postgresql+psycopg2"
 
+    if backend == "sqlite":
+        return "sqlite:///" + SQLITE_TEST_DATABASE_PATH
+
     return ("%(backend)s://%(user)s:%(passwd)s@localhost/%(database)s"
             % {'backend': backend, 'user': user, 'passwd': passwd,
                'database': database})

subunit2sql/tests/migrations/test_migrations.py

@@ -194,6 +194,17 @@ class TestWalkMigrations(base.TestCase):
         # build a fully populated postgresql database with all the tables
         self._walk_versions(engine)
 
+    def test_sqlite_opportunistically(self):
+        self.useFixture(fixtures.LockFixture('sqlite'))
+        self.useFixture(fixtures.SqliteConfFixture())
+
+        connect_string = db_test_utils.get_connect_string("sqlite")
+        engine = sqlalchemy.create_engine(connect_string)
+        self.engines["sqlitecitest"] = engine
+        self.test_databases["sqlitecitest"] = connect_string
+
+        self._walk_versions(engine)
+
     def _pre_upgrade_1f92cfe8a6d3(self, engine):
         tests = get_table(engine, 'tests')
         data = {'id': 'fake_test.id',

subunit2sql/tests/subunit2sql_fixtures.py

@@ -140,6 +140,27 @@ class PostgresConfFixture(config_fixture.Config):
         self._drop_db()
 
 
+class SqliteConfFixture(config_fixture.Config):
+    """Fixture to manage global conf settings."""
+    def _drop_db(self):
+        if os.path.exists(db_test_utils.SQLITE_TEST_DATABASE_PATH):
+            os.remove(db_test_utils.SQLITE_TEST_DATABASE_PATH)
+
+    def setUp(self):
+        super(SqliteConfFixture, self).setUp()
+        self.register_opts(options.database_opts, group='database')
+        self.register_opts(cli.MIGRATION_OPTS)
+        self.url = db_test_utils.get_connect_string("sqlite")
+        self.set_default('connection', self.url, group='database')
+        self.set_default('disable_microsecond_data_migration', False)
+        lockutils.set_defaults(lock_path='/tmp')
+        self._drop_db()
+        self.addCleanup(self.cleanup)
+
+    def cleanup(self):
+        self._drop_db()
+
+
 class LockFixture(lock_fixture.LockFixture):
     def __init__(self, name):
         lockutils.set_defaults(lock_path='/tmp')