Add test case to serialize result of simulation (#1869)

* add test case to serialize result of simulation

* add pickle comparison

---------

Co-authored-by: Jun Doi <doichan@jp.ibm.com>

test/terra/backends/aer_simulator/test_executors.py

@@ -13,13 +13,18 @@
 AerSimualtor options tests
 """
 import logging
+import json
 from math import ceil
 import concurrent.futures
+import pickle
+import tempfile
 
 from ddt import ddt
 from qiskit import QuantumCircuit, transpile
 from qiskit.circuit.random import random_circuit
+from qiskit.circuit.library import QuantumVolume
 from qiskit.quantum_info import Statevector
+from qiskit_aer.noise.noise_model import AerJSONEncoder
 from test.terra.reference import ref_kraus_noise
 from qiskit_aer.jobs import AerJob, AerJobSet
 from test.terra.backends.simulator_test_case import SimulatorTestCase, supported_methods
@@ -56,6 +61,32 @@ def run_random_circuits(backend, shots=None, **run_options):
     return result, circuits, targets
 
 
+class TestResultSerialization(SimulatorTestCase):
+    """Test seriallization of AerJob"""
+
+    def test_aer_job_json_dump(self):
+        circuit = QuantumVolume(4, seed=111)
+        circuit.measure_all()
+        backend = self.backend(method="statevector")
+        result = backend.run(transpile(circuit, backend)).result()
+        data = json.dumps(result, cls=AerJSONEncoder)
+        result_copy = json.loads(data)
+        self.compare_counts(result, [circuit], [result_copy["results"][0]["data"]["counts"]])
+
+    def test_aer_job_picklable(self):
+        circuit = QuantumVolume(4, seed=111)
+        circuit.measure_all()
+        backend = self.backend(method="statevector")
+        result = backend.run(transpile(circuit, backend)).result()
+
+        with tempfile.TemporaryFile() as f:
+            pickle.dump(result, f)
+            f.seek(0)
+            result_copy = pickle.load(f)
+
+        self.assertEqual(result.get_counts(), result_copy.get_counts())
+
+
 class CBFixture(SimulatorTestCase):
     """Extension tests for Aerbackend with cluster backend"""