New method to create a new Session object with a given id

qiskit_ibm_runtime/session.py

@@ -211,6 +211,19 @@ def service(self) -> QiskitRuntimeService:
         """
         return self._service
 
+    @classmethod
+    def from_id(
+        cls,
+        session_id: str,
+        service: Optional[QiskitRuntimeService] = None,
+        backend: Optional[Union[str, IBMBackend]] = None,
+        max_time: Optional[Union[int, str]] = None,
+    ) -> "Session":
+        """Construct a Session object with a given session_id"""
+        session = cls(service, backend, max_time)
+        session._session_id = session_id
+        return session
+
     def __enter__(self) -> "Session":
         set_cm_session(self)
         return self

releasenotes/notes/from_id-23fc85f3fbf01e0b.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Added new method ``Session.from_id`` which creates a new session with a given id.
+
+

test/integration/test_session.py

@@ -84,3 +84,18 @@ def test_using_correct_instance(self, service):
             job = sampler.run(ReferenceCircuits.bell(), shots=400)
             self.assertEqual(instance, backend._instance)
             self.assertEqual(instance, job.backend()._instance)
+
+    @run_integration_test
+    def test_session_from_id(self, service):
+        """Test creating a session from a given id"""
+        instance = self.dependencies.instance
+        backend = service.backend("ibmq_qasm_simulator", instance=instance)
+        with Session(service, backend=backend) as session:
+            sampler = Sampler(session=session)
+            job = sampler.run(ReferenceCircuits.bell(), shots=400)
+            session_id = job.session_id
+            session.close()
+        new_session = Session.from_id(backend=backend, session_id=session_id)
+        sampler = Sampler(session=new_session)
+        job = sampler.run(ReferenceCircuits.bell(), shots=400)
+        self.assertEqual(session_id, job.session_id)

test/unit/test_session.py

@@ -154,3 +154,11 @@ def test_global_service(self):
             service=FakeRuntimeService(channel="ibm_quantum", token="uvw"), backend="ibm_gotham"
         ) as session:
             self.assertEqual(session._service._account.token, "uvw")
+
+    def test_session_from_id(self):
+        """Create session with given session_id"""
+        service = MagicMock()
+        session_id = "123"
+        session = Session.from_id(session_id=session_id, service=service)
+        session.run(program_id="foo", inputs={})
+        self.assertEqual(session.session_id, session_id)