Tweak sensor value setter to validate dtype

.pre-commit-config.yaml

@@ -41,5 +41,5 @@ repos:
           'katcp-codec==0.1.0',
           'pytest==8.1.1',
           'types-decorator==5.1.1',
-          'typing-extensions==4.11.0'
+          'typing-extensions==4.11.0',
         ]

src/aiokatcp/core.py

@@ -79,6 +79,8 @@ class Address:
     _IPV6_RE = re.compile(r"^\[(?P<host>[^]]+)\](:(?P<port>\d+))?$")
 
     def __init__(self, host: _IPAddress, port: Optional[int] = None) -> None:
+        if not isinstance(host, typing.get_args(_IPAddress)):
+            raise TypeError(f"{host} is not of either {typing.get_args(_IPAddress)}")
         self._host = host
         self._port = port
 

src/aiokatcp/sensor.py

@@ -30,6 +30,7 @@
 import enum
 import functools
 import inspect
+import numbers
 import time
 import warnings
 import weakref
@@ -168,6 +169,7 @@ def __init__(
         self.stype = sensor_type
         type_info = core.get_type(sensor_type)
         self.type_name = type_info.name
+        self._core_type = type_info.type_
         self._classic_observers: Set[ClassicObserver[_T]] = set()
         self._delta_observers: Set[DeltaObserver[_T]] = set()
         self.name = name
@@ -177,7 +179,7 @@ def __init__(
         if default is None:
             value: _T = type_info.default(sensor_type)
         else:
-            value = default
+            value = self._cast_value_type(default)
         self._reading = Reading(time.time(), initial_status, value)
         if auto_strategy is None:
             self.auto_strategy = SensorSampler.Strategy.AUTO
@@ -186,6 +188,38 @@ def __init__(
         self.auto_strategy_parameters = tuple(auto_strategy_parameters)
         # TODO: should validate the parameters against the strategy.
 
+    def _cast_value_type(self, value: Any) -> _T:
+        """Coerce incoming value to the sensor type.
+
+        If it is compatible, cast it to the expected data type to ensure the
+        incoming value is in the required format. This also handles the special
+        case of :class:`core.Timestamp` where it is used with `float` type
+        interchangeably.
+
+        Raises
+        ------
+        TypeError
+            If the incoming `value` type is not compatible with the sensor's
+            core type.
+        """
+        if isinstance(value, self.stype):
+            # The value is not a special case and can be returned unchanged
+            return value
+        elif isinstance(value, self._core_type) and not issubclass(self._core_type, enum.Enum):
+            # The more general case where the value is not derived from stype
+            # but is derived from the registered base type. e.g. numpy reals
+            # don't derive from Python's float, but do derive from numbers.Real.
+            # Explicitly cast it into the desired type.
+            return self.stype(value)  # type: ignore [call-arg]
+        elif isinstance(value, numbers.Real) and self.stype is core.Timestamp:
+            # core.Timestamp can also be an int or float
+            return self.stype(value)  # type: ignore [call-arg]
+        else:
+            raise TypeError(
+                f"Value type {type(value)} is not compatible with Sensor type "
+                f"{self.stype} with core type {self._core_type}"
+            )
+
     def notify(self, reading: Reading[_T], old_reading: Reading[_T]) -> None:
         """Notify all observers of changes to this sensor.
 
@@ -198,10 +232,14 @@ def notify(self, reading: Reading[_T], old_reading: Reading[_T]) -> None:
             delta_observer(self, reading, old_reading=old_reading)
 
     def set_value(
-        self, value: _T, status: Optional[Status] = None, timestamp: Optional[float] = None
+        self, value: Any, status: Optional[Status] = None, timestamp: Optional[float] = None
     ) -> None:
         """Set the current value of the sensor.
 
+        Also validate that the incoming value type is compatible with the core
+        type of this sensor. If compatible, coerce it to an instance of the
+        :attr:`stype`.
+
         Parameters
         ----------
         value
@@ -214,12 +252,19 @@ def set_value(
         timestamp
             The time at which the sensor value was determined (seconds).
             If not given, it defaults to :func:`time.time`.
+
+        Raises
+        ------
+        TypeError
+            If the incoming `value` type is not compatible with the sensor's
+            core type.
         """
+        checked_value = self._cast_value_type(value)
         if timestamp is None:
             timestamp = time.time()
         if status is None:
-            status = self.status_func(value)
-        reading = Reading(timestamp, status, value)
+            status = self.status_func(checked_value)
+        reading = Reading(timestamp, status, checked_value)
         old_reading = self._reading
         self._reading = reading
         self.notify(reading, old_reading)
@@ -233,7 +278,7 @@ def value(self) -> _T:
         return self.reading.value
 
     @value.setter
-    def value(self, value: _T) -> None:
+    def value(self, value: Any) -> None:
         self.set_value(value)
 
     @property

tests/test_sensor.py

@@ -30,15 +30,19 @@
 """
 
 import asyncio
+import enum
 import gc
 import unittest
 import weakref
-from typing import List, Optional
+from fractions import Fraction
+from ipaddress import IPv4Address
+from typing import Any, List, Optional, Type, TypeVar
 from unittest import mock
 from unittest.mock import create_autospec
 
 import pytest
 
+from aiokatcp.core import Address, Timestamp
 from aiokatcp.sensor import (
     AggregateSensor,
     Reading,
@@ -49,6 +53,8 @@
     _weak_callback,
 )
 
+_T = TypeVar("_T")
+
 
 @pytest.mark.parametrize(
     "status,valid",
@@ -80,6 +86,88 @@ def status_func(value):
     assert sensor.status == Sensor.Status.NOMINAL
 
 
+class MyEnum(enum.Enum):
+    ZERO = 0
+    ONE = 1
+
+
+class OtherEnum(enum.Enum):
+    ABC = 0
+    DEF = 1
+
+
+@pytest.mark.parametrize(
+    "sensor_type,compatible_value",
+    [
+        (bool, True),
+        (int, 1234),
+        (float, 1234),
+        (float, 1234.5),
+        (float, Fraction(8190, 64)),
+        (str, "one-two-three-four"),
+        (bytes, b"one-two-three-four"),
+        (Address, Address(IPv4Address("1.2.3.4"))),
+        (Timestamp, 12345678),
+        (MyEnum, MyEnum.ONE),
+    ],
+)
+@pytest.mark.parametrize("initialise_sensor", [True, False])
+def test_sensor_value_setter_success(
+    sensor_type: Type,
+    compatible_value: Any,
+    initialise_sensor: bool,
+) -> None:
+    """Check a compatible value against a sensor type.
+
+    Using `initialise_sensor`, this test checks `compatible_value` either as a
+    default sensor value, or as a new value to an existing sensor.
+    """
+    sensor = Sensor(
+        sensor_type,
+        "test-sensor",
+        default=compatible_value if initialise_sensor else None,
+    )
+    if not initialise_sensor:
+        sensor.value = compatible_value
+    assert sensor.value == compatible_value
+    assert isinstance(sensor.value, sensor_type)
+
+
+@pytest.mark.parametrize(
+    "sensor_type,bad_value",
+    [
+        (bool, "True"),
+        (int, "1234"),
+        (int, 1234.5),
+        (float, 1 + 2j),
+        (str, {"a": 1}),
+        (str, b"bytes"),
+        (bytes, "str"),
+        (Address, "0.0.0.0"),
+        (Timestamp, "12345678"),
+        (MyEnum, OtherEnum.ABC),
+    ],
+)
+def test_sensor_value_setter_failure(
+    sensor_type: Type[_T],
+    bad_value: Any,
+) -> None:
+    """Check an incompatible value for a sensor.
+
+    Check the `bad_value` is not compatible both as a new value for an existing
+    sensor and as an initial value for a new sensor.
+    """
+    sensor = Sensor(
+        sensor_type,
+        "test-sensor",
+    )
+    with pytest.raises(TypeError):
+        sensor.value = bad_value
+
+    with pytest.raises(TypeError):
+        Sensor(sensor_type, "test-sensor", default=bad_value)
+
+
 @pytest.fixture
 def classic_observer():
     def classic(sensor, reading):