More specific return type for root_instrument

Author: jenshnielsen

src/qcodes/instrument/channel.py

@@ -26,6 +26,7 @@
 
     from typing_extensions import Unpack
 
+    from .instrument import Instrument
     from .instrument_base import InstrumentBaseKWArgs
 
 
@@ -86,8 +87,14 @@ def parent(self) -> _TIB_co:
         return self._parent
 
     @property
-    def root_instrument(self) -> InstrumentBase:
-        return self._parent.root_instrument
+    def root_instrument(self) -> Instrument:
+        # the root instrument is the top level parent of this module, we need to
+        # go up the parent hierarchy until we find an object that returns itself as the parent, this should be the root instrument. We also
+        # this is required to be an Instrument.
+        # Once 3.13 is the minimum supported version
+        # consider replacing with a generic parameter with a default
+        # value of Instrument.
+        return cast("Instrument", self._parent.root_instrument)
 
     @property
     def name_parts(self) -> list[str]:

src/qcodes/instrument/instrument_base.py

@@ -18,7 +18,7 @@
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Mapping, Sequence
-    from typing import NotRequired
+    from typing import NotRequired, Self
 
     from qcodes.instrument.channel import ChannelTuple, InstrumentModule
     from qcodes.logger.instrument_logger import InstrumentLoggerAdapter
@@ -579,7 +579,7 @@ def ancestors(self) -> tuple[InstrumentBase, ...]:
             return (self,)
 
     @property
-    def root_instrument(self) -> InstrumentBase:
+    def root_instrument(self) -> Self:
         """
         The topmost parent of this module.
 

tests/drivers/keysight_b1500/b1500_driver_tests/test_b1517a_smu.py

@@ -433,7 +433,7 @@ def test_iv_sweep_delay(smu: KeysightB1517A) -> None:
     smu.iv_sweep.step_delay(0.01)
     smu.iv_sweep.trigger_delay(0.1)
     smu.iv_sweep.measure_delay(15.4)
-
+    assert isinstance(mainframe, MagicMock)
     mainframe.write.assert_has_calls(
         [
             call("WT 43.12,0.0,0.0,0.0,0.0"),

tests/drivers/keysight_b1500/b1500_driver_tests/test_b1520a_cmu.py

@@ -179,7 +179,7 @@ def test_get_post_sweep_voltage_cond(cmu: KeysightB1520A) -> None:
 
 def test_cv_sweep_delay(cmu: KeysightB1520A) -> None:
     mainframe = cmu.root_instrument
-
+    assert isinstance(mainframe, MagicMock)
     mainframe.ask.return_value = "WTDCV0.0,0.0,0.0,0.0,0.0"
 
     cmu.cv_sweep.hold_time(1.0)
@@ -192,6 +192,7 @@ def test_cv_sweep_delay(cmu: KeysightB1520A) -> None:
 
 def test_cmu_sweep_steps(cmu: KeysightB1520A) -> None:
     mainframe = cmu.root_instrument
+    assert isinstance(mainframe, MagicMock)
     mainframe.ask.return_value = "WDCV3,1,0.0,0.0,1"
     cmu.cv_sweep.sweep_start(2.0)
     cmu.cv_sweep.sweep_end(4.0)
@@ -208,6 +209,7 @@ def test_cv_sweep_voltages(cmu: KeysightB1520A) -> None:
     end = 1.0
     steps = 5
     return_string = f"WDCV3,1,{start},{end},{steps}"
+    assert isinstance(mainframe, MagicMock)
     mainframe.ask.return_value = return_string
 
     cmu.cv_sweep.sweep_start(start)
@@ -226,6 +228,7 @@ def test_sweep_modes(cmu: KeysightB1520A) -> None:
     steps = 5
     mode = constants.SweepMode.LINEAR_TWO_WAY
     return_string = f"WDCV3,{mode},{start},{end},{steps}"
+    assert isinstance(mainframe, MagicMock)
     mainframe.ask.return_value = return_string
 
     cmu.cv_sweep.sweep_start(start)
@@ -249,6 +252,7 @@ def test_run_sweep(cmu: KeysightB1520A) -> None:
         f"0.0000;WDCV3,"
         f"1,{start},{end},{steps};ACT0,1"
     )
+    assert isinstance(mainframe, MagicMock)
     mainframe.ask.return_value = return_string
     cmu.setup_fnc_already_run = True
     cmu.impedance_model(constants.IMP.MeasurementMode.G_X)

tests/drivers/keysight_b1500/b1500_driver_tests/test_sampling_measurement.py

@@ -83,6 +83,7 @@ def test_sampling_measurement(
     actual_data = smu.sampling_measurement_trace.get()
 
     np.testing.assert_allclose(actual_data, data_to_return, atol=1e-3)
+    assert isinstance(smu.root_instrument.ask, Mock)
     smu.root_instrument.ask.assert_called_with("XE")