Run tests in in-memory SQLite db

Signed-off-by: Chenxiong Qi <cqi@redhat.com>

conf/config.py

@@ -98,8 +98,7 @@ class TestConfiguration(BaseConfiguration):
     BUILD_LOGS_NAME_FORMAT = "build-{id}.log"
     LOG_BACKEND = "console"
     LOG_LEVEL = "debug"
-    SQLALCHEMY_DATABASE_URI = environ.get(
-        "DATABASE_URI", "sqlite:///{0}".format(path.join(dbdir, "mbstest.db")))
+    SQLALCHEMY_DATABASE_URI = environ.get("DATABASE_URI", "sqlite:///:memory:")
     DEBUG = True
     MESSAGING = "in_memory"
     PDC_URL = "https://pdc.fedoraproject.org/rest_api/v1"

tests/__init__.py

@@ -109,6 +109,7 @@ def clean_database(add_platform_module=True, add_default_arches=True):
     # clean_database is usually called before a test run. So, it makes no sense
     # to keep any changes in the transaction made by previous test.
     db_session.remove()
+    db_session.configure(bind=db.session.get_bind())
 
     db.drop_all()
     db.create_all()