+# Copyright 2019 Nokia
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import itertools
+
+
+class UserGen(object):
+
+ def __init__(self, roles_len):
+ self._roles_len = roles_len
+ self._usergens = {}
+
+ def create_username(self, roles):
+ if not roles:
+ return 'no_roles'
+ if len(roles) == self._roles_len:
+ return 'all_roles'
+ return next(self._get_user_gen(sorted(roles)[0]))
+
+ def _get_user_gen(self, base):
+ if base not in self._usergens:
+ self._usergens[base] = self._user_gen(base)
+ return self._usergens[base]
+
+ @staticmethod
+ def _user_gen(base):
+ for idx in itertools.count(): # pragma: no branch
+ yield '{base}{idx}'.format(base=base, idx=idx)