Fixup sqlite engine for tests

According to
http://docs.sqlalchemy.org/en/latest/dialects/sqlite.html#pysqlite-serializable

tuning_box/db.py

@@ -14,6 +14,7 @@ import functools
 import json
 
 import flask_sqlalchemy
+import sqlalchemy.event
 from sqlalchemy import types
 
 db = flask_sqlalchemy.SQLAlchemy()
@@ -129,3 +130,15 @@ class EnvironmentSchemaValues(db.Model):
     __table_args__ = (
         db.UniqueConstraint(environment_id, schema_id, level_value_id),
     )
+
+
+def fix_sqlite():
+    engine = db.engine
+
+    @sqlalchemy.event.listens_for(engine, "connect")
+    def _connect(dbapi_connection, connection_record):
+        dbapi_connection.isolation_level = None
+
+    @sqlalchemy.event.listens_for(engine, "begin")
+    def _begin(conn):
+        conn.execute("BEGIN")

tuning_box/tests/test_app.py

@@ -45,6 +45,7 @@ class TestApp(base.TestCase):
         self.app = app.build_app()
         self.app.config["SQLALCHEMY_DATABASE_URI"] = 'sqlite:///'
         with self.app.app_context():
+            db.fix_sqlite()
             db.db.create_all()
         self.client = Client(self.app)
 

tuning_box/tests/test_db.py

@@ -24,6 +24,7 @@ class _DBTestCase(base.TestCase):
         self.app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False  # no warning
         db.db.init_app(self.app)
         with self.app.app_context():
+            db.fix_sqlite()
             db.db.create_all()