Remove deprecated use of qiskit.test.mock (#1547)

* Remove deprecated use of qiskit.test.mock

Terra 0.21 triggers deprecation warnings for `qiskit.test.mock`, in
favour of `qiskit.providers.fake_provider`, which has been available
since Terra 0.20.  The only uses are in the tests, but it still
technically requires a version bump in the Terra requirement.  It's
fairly likely something else will bump the Terra version further before
release of Aer 0.11.

* Flatten unnecessarily nested import

This is also necessary because the submodule structure of
`qiskit.providers.fake_provider` is not guaranteed to be a public
interface, especially in Terra 0.20.

Co-authored-by: Hiroshi Horii <[email protected]>

releasenotes/notes/terra-version-bump-68eac37136428805.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    The required version of Qiskit Terra has been bumped to 0.20.0.

setup.py

@@ -83,7 +83,7 @@ def install_needed_req(import_name, package_name=None, min_version=None, max_ver
 if not _DISABLE_CONAN:
     setup_requirements.append('conan>=1.22.2')
 
-requirements = common_requirements + ['qiskit-terra>=0.19.1', 'scipy>=1.0']
+requirements = common_requirements + ['qiskit-terra>=0.20.0', 'scipy>=1.0']
 
 if not hasattr(setuptools,
                'find_namespace_packages') or not inspect.ismethod(

test/terra/backends/test_config_pulse_simulator.py

@@ -20,8 +20,7 @@
 from test.terra import common
 
 from qiskit import QuantumCircuit, transpile, schedule
-from qiskit.test.mock.backends.armonk.fake_armonk import FakeArmonk
-from qiskit.test.mock.backends.athens.fake_athens import FakeAthens
+from qiskit.providers.fake_provider import FakeArmonk, FakeAthens
 
 from qiskit.providers.aer.backends import PulseSimulator
 from qiskit.pulse import (Schedule, Play, ShiftPhase, SetPhase, Delay, Acquire,

test/terra/backends/test_pulse_simulator.py

@@ -36,7 +36,7 @@
 from qiskit.providers.aer.pulse.system_models.hamiltonian_model import HamiltonianModel
 from qiskit.providers.models.backendconfiguration import UchannelLO
 from qiskit.providers.aer.aererror import AerError
-from qiskit.test.mock import FakeArmonk
+from qiskit.providers.fake_provider import FakeArmonk
 
 from .pulse_sim_independent import (simulate_1q_model,
                                     simulate_2q_exchange_model,

test/terra/pulse/test_system_models.py

@@ -18,10 +18,10 @@
 import numpy as np
 from numpy.linalg import norm
 from test.terra.common import QiskitAerTestCase
-from qiskit.test.mock import FakeOpenPulse2Q
+from qiskit.providers.fake_provider import FakeOpenPulse2Q
 from qiskit.providers.aer.pulse.system_models.pulse_system_model import PulseSystemModel
 from qiskit.providers.aer.pulse.system_models.hamiltonian_model import HamiltonianModel
-from qiskit.test.mock import FakeArmonk
+from qiskit.providers.fake_provider import FakeArmonk
 from qiskit.providers.models.backendconfiguration import UchannelLO