add tests for Unit

tests/unit/datatypes/test_unit.py

@@ -0,0 +1,118 @@
+import json
+import re
+import pytest
+
+from sdRDM.base.datatypes.unit import BaseUnit, Unit
+from astropy.units import UnitBase, Unit as AstroUnit
+
+
+class TestUnit:
+    @pytest.mark.unit
+    def test_simple_unit_from_string(self):
+        # Arrange
+        unit_string = "m"
+
+        # Act
+        unit = Unit.from_string(unit_string)
+
+        # Assert
+        assert unit.name == "m"
+        assert unit.bases == [
+            BaseUnit(
+                kind="m",
+                exponent=1,
+                scale=1,
+            )
+        ]
+
+    @pytest.mark.unit
+    def test_composite_unit_from_string(self):
+        # Arrange
+        unit_string = "m/s"
+
+        # Act
+        unit = Unit.from_string(unit_string)
+
+        # Assert
+        assert unit.name == "m / s"
+        assert unit.bases == [
+            BaseUnit(
+                kind="m",
+                exponent=1,
+                scale=1,
+            ),
+            BaseUnit(
+                kind="s",
+                exponent=-1,
+                scale=1,
+            ),
+        ]
+
+    @pytest.mark.unit
+    def test_dimensionless_unit_from_string(self):
+        # Arrange
+        unit_string = "dimensionless"
+
+        # Act
+        unit = Unit.from_string(unit_string)
+
+        # Assert
+        assert unit.name == "dimensionless"
+        assert unit.bases == []
+
+    @pytest.mark.unit
+    def test_json_serialization(self):
+        # Arrange
+        unit_string = "m/s"
+
+        # Act
+        unit = Unit.from_string(unit_string)
+        unit_json = unit.json(exclude={"id"})
+
+        # Assert
+        expected_json = {
+            "name": "m / s",
+            "bases": [
+                {
+                    "kind": "m",
+                    "exponent": 1,
+                    "scale": 1,
+                },
+                {
+                    "kind": "s",
+                    "exponent": -1,
+                    "scale": 1,
+                },
+            ],
+        }
+
+        assert json.loads(unit_json) == expected_json
+
+    @pytest.mark.unit
+    def test_to_unit_string(self):
+        # Arrange
+        unit_string = "m/s"
+        unit = Unit.from_string(unit_string)
+
+        # Act
+        string = unit.to_unit_string()
+
+        # Assert
+        assert string == "m / s"
+
+    @pytest.mark.unit
+    def test_xml_serialization(self):
+        # Arrange
+        unit_string = "m/s"
+
+        # Act
+        unit = Unit.from_string(unit_string)
+        unit_xml = unit.xml()
+
+        # Assert
+        expected_xml = '<?xml version="1.0" encoding="UTF-8"?><Unit  name="m / s">  <listOfUnits>    <unit scale="1.0" kind="m" exponent="1.0"/>    <unit scale="1.0" kind="s" exponent="-1.0"/>  </listOfUnits></Unit>'
+
+        unit_xml = unit_xml.replace("\n", "").replace("'", '"')
+        unit_xml = re.sub(r'id="[\w-]+"', "", unit_xml)
+
+        assert unit_xml == expected_xml