Traceback (most recent call last):
        File "/usr/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
          return self.cursor.execute(sql, params)
      psycopg2.IntegrityError: null value in column "username" violates not-null constraint
      DETAIL:  Failing row contains (2054, pbkdf2_sha256$36000$xGk75O81ZdkC$jtzL8Fjm4/XnQDQBCwdQJH9J6up2x6O..., null, f, 2018-02-13 15:39:04.418477+02, null, {}, null, staff, null, null).


      The above exception was the direct cause of the following exception:

      Traceback (most recent call last):
        File "/usr/lib/python3.6/site-packages/behave/model.py", line 1456, in run
          match.run(runner.context)
        File "/usr/lib/python3.6/site-packages/behave/model.py", line 1903, in run
          self.func(context, *args, **kwargs)
        File "features/steps/steps.py", line 74, in impl
          context.actionwords.create_staff_user()
        File "/app/features/steps/actionwords_implemented.py", line 116, in create_staff_user
          model_create_staff_user()
        File "/app/test_helpers/context_helpers.py", line 289, in wrapped
          value = funct(*args, **kwargs)
        File "/app/test_helpers/model_helpers.py", line 84, in model_create_staff_user
          user = manager.create_user(username="staff", password="pass")
        File "/app/microfinance/apps/authentication/models.py", line 218, in create_user
          res = self._create_user('staff', 'email_client', username, password)
        File "/app/microfinance/apps/authentication/models.py", line 209, in _create_user
          is_superuser=user_type == 'admin',
        File "/usr/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
          return getattr(self.get_queryset(), name)(*args, **kwargs)
        File "/usr/lib/python3.6/site-packages/django/db/models/query.py", line 394, in create
          obj.save(force_insert=True, using=self.db)
        File "/usr/lib/python3.6/site-packages/django/contrib/auth/base_user.py", line 80, in save
          super(AbstractBaseUser, self).save(*args, **kwargs)
        File "/usr/lib/python3.6/site-packages/django/db/models/base.py", line 808, in save
          force_update=force_update, update_fields=update_fields)
        File "/usr/lib/python3.6/site-packages/django/db/models/base.py", line 838, in save_base
          updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
        File "/usr/lib/python3.6/site-packages/django/db/models/base.py", line 924, in _save_table
          result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
        File "/usr/lib/python3.6/site-packages/django/db/models/base.py", line 963, in _do_insert
          using=using, raw=raw)
        File "/usr/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
          return getattr(self.get_queryset(), name)(*args, **kwargs)
        File "/usr/lib/python3.6/site-packages/django/db/models/query.py", line 1076, in _insert
          return query.get_compiler(using=using).execute_sql(return_id)
        File "/usr/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1112, in execute_sql
          cursor.execute(sql, params)
        File "/usr/lib/python3.6/site-packages/django/db/backends/utils.py", line 79, in execute
          return super(CursorDebugWrapper, self).execute(sql, params)
        File "/usr/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
          return self.cursor.execute(sql, params)
        File "/usr/lib/python3.6/site-packages/django/db/utils.py", line 94, in __exit__
          six.reraise(dj_exc_type, dj_exc_value, traceback)
        File "/usr/lib/python3.6/site-packages/django/utils/six.py", line 685, in reraise
          raise value.with_traceback(tb)
        File "/usr/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
          return self.cursor.execute(sql, params)
      django.db.utils.IntegrityError: null value in column "username" violates not-null constraint
      DETAIL:  Failing row contains (2054, pbkdf2_sha256$36000$xGk75O81ZdkC$jtzL8Fjm4/XnQDQBCwdQJH9J6up2x6O..., null, f, 2018-02-13 15:39:04.418477+02, null, {}, null, staff, null, null).