fix import of OP_FIELD_NAME
@@ -15,6 +15,7 @@ from plenum.common.types import f
from plenum.common.util import bootstrapClientKeys
from plenum.test.test_stack import StackedTester, getTestableStack
from plenum.test.testable import Spyable
+from plenum.common.constants import OP_FIELD_NAME
logger = getlogger()
