Added the Session.from_id method

qiskit_ibm_runtime/session.py

@@ -230,6 +230,19 @@ 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

test/unit/test_session.py

@@ -163,3 +163,11 @@ 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)