feat: adding support for units

With `pint` as the unit package, the user can now define Quantities as
attributes of their DataService class. This will be rendered as a float
in the frontend application with the unit as an additional field
appended to the form.

tests/test_units.py

@@ -0,0 +1,115 @@
+from typing import Any
+
+from pytest import CaptureFixture
+
+import pydase.units as u
+from pydase.data_service.data_service import DataService
+
+
+def test_DataService_setattr(capsys: CaptureFixture) -> None:
+    class ServiceClass(DataService):
+        voltage = 1.0 * u.units.V
+        _current: u.Quantity = 1.0 * u.units.mA
+
+        @property
+        def current(self) -> u.Quantity:
+            return self._current
+
+        @current.setter
+        def current(self, value: Any) -> None:
+            self._current = value
+
+    service = ServiceClass()
+
+    # You can just set floats to the Quantity objects. The DataService __setattr__ will
+    # automatically convert this
+    service.voltage = 10.0  # type: ignore
+    service.current = 1.5
+
+    assert service.voltage == 10.0 * u.units.V  # type: ignore
+    assert service.current == 1.5 * u.units.mA
+    captured = capsys.readouterr()
+
+    expected_output = sorted(
+        [
+            "ServiceClass.voltage = 10.0 V",
+            "ServiceClass.current = 1.5 mA",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert actual_output == expected_output
+
+    service.voltage = 12.0 * u.units.V  # type: ignore
+    service.current = 1.51 * u.units.A
+    assert service.voltage == 12.0 * u.units.V  # type: ignore
+    assert service.current == 1.51 * u.units.A
+    captured = capsys.readouterr()
+
+    expected_output = sorted(
+        [
+            "ServiceClass.voltage = 12.0 V",
+            "ServiceClass.current = 1.51 A",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert actual_output == expected_output
+
+
+def test_convert_to_quantity() -> None:
+    assert u.convert_to_quantity(1.0, unit="V") == 1.0 * u.units.V
+    assert u.convert_to_quantity(1, unit="mV") == 1.0 * u.units.mV
+    assert u.convert_to_quantity({"magnitude": 12, "unit": "kV"}) == 12.0 * u.units.kV
+    assert u.convert_to_quantity(1.0 * u.units.mV) == 1.0 * u.units.mV
+
+
+def test_update_DataService_attribute(capsys: CaptureFixture) -> None:
+    class ServiceClass(DataService):
+        voltage = 1.0 * u.units.V
+        _current: u.Quantity = 1.0 * u.units.mA
+
+        @property
+        def current(self) -> u.Quantity:
+            return self._current
+
+        @current.setter
+        def current(self, value: Any) -> None:
+            self._current = value
+
+    service = ServiceClass()
+
+    service.update_DataService_attribute(
+        path_list=[], attr_name="voltage", value=1.0 * u.units.mV
+    )
+    captured = capsys.readouterr()
+
+    expected_output = sorted(
+        [
+            "ServiceClass.voltage = 1.0 mV",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert actual_output == expected_output
+
+    service.update_DataService_attribute(path_list=[], attr_name="voltage", value=2)
+    captured = capsys.readouterr()
+
+    expected_output = sorted(
+        [
+            "ServiceClass.voltage = 2.0 mV",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert actual_output == expected_output
+
+    service.update_DataService_attribute(
+        path_list=[], attr_name="voltage", value={"magnitude": 123, "unit": "kV"}
+    )
+    captured = capsys.readouterr()
+
+    expected_output = sorted(
+        [
+            "ServiceClass.voltage = 123.0 kV",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert actual_output == expected_output