Test that retrieved jobs come from their appropriate backend

CHANGELOG.rst

@@ -37,6 +37,7 @@ Changed
   Qiskit Terra package.
 - The exception hierarchy has been revised: the package base exception is
   ``IBMQError``, and they have been grouped in ``.exception`` modules. (#5)
+- Ensured that retrieved jobs come from their appropriate backend (#23)
 
 
 

qiskit/providers/ibmq/ibmqbackend.py

@@ -193,7 +193,15 @@ def retrieve_job(self, job_id):
             IBMQBackendError: if retrieval failed
         """
         try:
-            job_info = self._api.get_status_job(job_id)
+            job_info = self._api.get_job(job_id)
+            if job_info['backend']['name'] != self.name():
+                warnings.warn('Job "{}" belongs to another backend than the one queried. '
+                              'The query was made on backend "{}", '
+                              'but the job actually belongs to backend "{}".'
+                              .format(job_id, job_info['backend']['name'], self.name()))
+                raise IBMQBackendError('Failed to get job "{}": '
+                                       'job does not belong to backend "{}".'
+                                       .format(job_id, job_info['backend']['name']))
             if 'error' in job_info:
                 raise IBMQBackendError('Failed to get job "{}": {}'
                                        .format(job_id, job_info['error']))

test/ibmq/test_ibmq_job.py

@@ -269,6 +269,31 @@ def test_retrieve_job(self, qe_token, qe_url):
         else:
             self.assertEqual(job.qobj(), None)
 
+    @slow_test
+    @requires_qe_access
+    def test_retrieve_job_uses_appropriate_backend(self, qe_token, qe_url):
+        """Test that retrieved jobs come from their appropriate backend."""
+        IBMQ.enable_account(qe_token, qe_url)
+        simulator_backend = IBMQ.get_backend('ibmq_qasm_simulator')
+        backends = IBMQ.backends(simulator=False)
+        real_backend = least_busy(backends)
+
+        qobj_sim = compile(self._qc, simulator_backend)
+        job_sim = simulator_backend.run(qobj_sim)
+
+        qobj_real = compile(self._qc, real_backend)
+        job_real = real_backend.run(qobj_real)
+
+        # test a retrieved job's backend is the same as the queried backend
+        self.assertEqual(simulator_backend.retrieve_job(job_sim.job_id()).backend().name(),
+                         simulator_backend.name())
+        self.assertEqual(real_backend.retrieve_job(job_real.job_id()).backend().name(),
+                         real_backend.name())
+
+        # test retrieve requests for jobs that exist on other backends throw errors
+        self.assertRaises(IBMQBackendError, simulator_backend.retrieve_job, job_real.job_id())
+        self.assertRaises(IBMQBackendError, real_backend.retrieve_job, job_sim.job_id())
+
     @requires_qe_access
     def test_retrieve_job_error(self, qe_token, qe_url):
         """Test retrieving an invalid job."""