units: support for offset units, add tests (#693)

Author: lukaspie

src/pynxtools/units/__init__.py

@@ -167,6 +167,6 @@ def is_valid_unit(unit: str):
         if ureg.Unit(unit) == ureg.Unit("pixel") and str(expected_dim) == "[length]":
             return True
 
-        actual_dim = (1 * ureg(unit)).dimensionality
+        actual_dim = ureg.Quantity(1, unit).to_base_units().dimensionality
 
         return actual_dim == expected_dim

tests/units/test_units.py

@@ -0,0 +1,28 @@
+import pytest
+
+from pynxtools.units import NXUnitSet
+
+
+@pytest.mark.parametrize(
+    "unit_category,unit,expected",
+    [
+        ("NX_LENGTH", "meter", True),
+        ("NX_LENGTH", "m", True),
+        ("NX_LENGTH", "second", False),
+        ("NX_TEMPERATURE", "kelvin", True),
+        ("NX_TEMPERATURE", "celsius", True),  # offset unit
+        ("NX_TEMPERATURE", "degC", True),  # alias
+        ("NX_TEMPERATURE", "second", False),
+        ("NX_ANY", "meter", True),
+        ("NX_ANY", "", True),  # empty allowed
+        ("NX_ANY", "foobar", False),  # unknown unit not allowed for NX_ANY
+        ("NX_LENGTH", "foobar", False),  # unknown unit not allowed
+        ("NX_LENGTH", "pixel", True),  # pixel is accepted as length
+        ("NX_DIMENSIONLESS", "", True),
+        ("NX_DIMENSIONLESS", "meter", False),
+        ("NX_UNITLESS", "", True),
+        ("NX_UNITLESS", "meter", False),
+    ],
+)
+def test_matches(unit_category, unit, expected):
+    assert NXUnitSet.matches(unit_category, unit) == expected