Does not exponentiate non-dimensional dimensions and composite dimensions

Author: Maxcode123

src/property_utils/tests/units/test_descriptors.py

@@ -29,13 +29,15 @@
     Unit5,
     Unit6,
     Unit7,
+    Unit9,
     dimension_1,
     dimension_2,
     dimension_3,
     dimension_4,
     dimension_5,
     dimension_6,
     dimension_7,
+    dimension_9,
     generic_dimension_1,
     generic_dimension_2,
     generic_dimension_3,
@@ -466,6 +468,22 @@ def test_with_none(self):
         self.assertResultRaises(DescriptorExponentError)
 
 
+@add_to(MeasurementUnit_test_suite)
+class TestNonDimensionalMeasurementUnitExponentiation(TestDescriptor):
+    produced_type = Dimension
+
+    def subject(self, value):
+        return Unit9.NON_DIMENSIONAL**value
+
+    @args({"value": 2})
+    def test_with_positive_int(self):
+        self.assert_result("")
+
+    @args({"value": -10})
+    def test_with_negative_int(self):
+        self.assert_result("")
+
+
 @add_to(AliasMeasurementUnit_test_suite)
 class TestAliasMeasurementUnitFromDescriptor(TestDescriptor):
     def subject(self, descriptor):
@@ -1372,6 +1390,19 @@ def subject(self, value):
         return dimension_1() ** value
 
 
+@add_to(Dimension_test_suite)
+class TestNonDimensionalDimensionExponentiation(
+    TestNonDimensionalMeasurementUnitExponentiation
+):
+    """
+    Repeat all tests in `TestNonDimensionalMeasurementUnitExponentiation` but with
+    dimension_9() as descriptor.
+    """
+
+    def subject(self, value):
+        return dimension_9() ** value
+
+
 @add_to(Dimension_test_suite)
 class TestExponentiatedDimensionExponentiation(TestDescriptor):
     produced_type = Dimension

src/property_utils/units/descriptors.py

@@ -484,6 +484,9 @@ def __pow__(self, power: float) -> "Dimension":
             >>> LengthUnit.FEET**3
             <Dimension: ft^3>
         """
+        # always keep non dimensional units to the first power
+        power = 1 if self.is_non_dimensional() else power
+
         return Dimension(self, power)
 
     def __hash__(self) -> int:
@@ -1025,7 +1028,10 @@ def __pow__(self, power: float) -> "Dimension":
                 f"invalid exponent: {{ value: {power}, type: {type(power)} }};"
                 " expected float or int. "
             )
-        self.power *= power
+        if self.unit.is_non_dimensional():
+            self.power = 1
+        else:
+            self.power *= power
         return self
 
     def __eq__(self, dimension) -> bool: