Fix TypeError in Measurement.with_precision() when None is passed.

openhtf/core/measurements.py

@@ -146,6 +146,10 @@ def with_args(self, **kwargs: Any) -> '_ConditionalValidator':
     return self
 
 
+def _round_value(value: Any, ndigits: int) -> Any:
+  return round(value, ndigits=ndigits) if value is not None else None
+
+
 def _coordinates_len(coordinates: Any) -> int:
   """Returns count of measurement coordinates.
 
@@ -397,7 +401,9 @@ def with_precision(self, precision: int) -> 'Measurement':
     if not isinstance(precision, int):
       raise TypeError('Precision must be specified as an int, not %s' %
                       type(precision))
-    return self.with_transform(functools.partial(round, ndigits=precision))
+    return self.with_transform(
+        functools.partial(_round_value, ndigits=precision)
+    )
 
   def with_transform(self, transform_fn: Callable[[Any], Any]) -> 'Measurement':
     """Set the transform function."""

test/core/measurements_test.py

@@ -123,6 +123,30 @@ def test_precision(self):
     m.measured_value[42] = 1.2346
     self.assertAlmostEqual(m.measured_value[42], 1.235)
 
+  def test_precision_handles_none(self):
+    """Check that with_precision handles None values gracefully."""
+    m = htf.Measurement('meas_with_precision').with_precision(3)
+    m.measured_value.set(None)
+    self.assertIsNone(m.measured_value.value)
+
+    m_dim = htf.Measurement('meas_with_precision_and_dims').with_precision(
+        3
+    ).with_dimensions('x')
+    m_dim.measured_value[42] = None
+    self.assertIsNone(m_dim.measured_value[42])
+
+  def test_precision_with_validator_none(self):
+    """Check that with_precision with InRange validator handles None without crashing."""
+    m = (
+        htf.Measurement('meas_with_precision_and_range')
+        .with_precision(2)
+        .in_range(1.0, 5.0)
+    )
+    m.measured_value.set(None)
+    m.notify_value_set()
+    self.assertEqual(m.outcome, measurements.Outcome.FAIL)
+    self.assertIsNone(m.measured_value.value)
+
   def test_cache_same_object(self):
     m = htf.Measurement('measurement')
     basetypes0 = m.as_base_types()