Remove marshmallow dependency

qiskit/providers/ibmq/ibmqsingleprovider.py

@@ -10,11 +10,10 @@
 import logging
 from collections import OrderedDict
 
-from marshmallow import ValidationError
-
 from qiskit.providers import BaseProvider
 from qiskit.providers.models import BackendConfiguration
 from qiskit.providers.providerutils import filter_backends
+from qiskit.validation.exceptions import ModelValidationError
 
 from .api import IBMQConnector
 from .ibmqbackend import IBMQBackend
@@ -101,7 +100,7 @@ def _discover_remote_backends(self):
                     provider=self._ibm_provider,
                     credentials=self.credentials,
                     api=self._api)
-            except ValidationError as ex:
+            except ModelValidationError as ex:
                 logger.warning(
                     'Remote backend "%s" could not be instantiated due to an '
                     'invalid config: %s',

requirements.txt

@@ -1,4 +1,3 @@
 qiskit-terra>=0.7,<0.8
-marshmallow>=2.17.0,<3
 requests>=2.19
 requests-ntlm>=1.1.0

setup.py

@@ -11,7 +11,6 @@
 
 requirements = [
     "qiskit-terra>=0.7,<0.8",
-    "marshmallow>=2.17.0,<3",
     "requests>=2.19",
     "requests-ntlm>=1.1.0",
 ]

test/ibmq/test_registration.py

@@ -105,8 +105,10 @@ def test_save_duplicate_accounts(self):
         """Test saving the same credentials twice."""
         with custom_qiskitrc(), mock_ibmq_provider():
             IBMQ.save_account('QISKITRC_TOKEN')
-            IBMQ.save_account('QISKITRC_TOKEN')
+            with self.assertWarns(UserWarning) as context_manager:
+                IBMQ.save_account('QISKITRC_TOKEN')
 
+            self.assertIn('Set overwrite', str(context_manager.warning))
             # Compare the session accounts with the ones stored in file.
             stored_accounts = read_credentials_from_qiskitrc()
             self.assertEqual(len(stored_accounts), 1)