from pint.converters import OffsetConverter, ScaleConverter
from pint.definitions import (
AliasDefinition,
Definition,
DimensionDefinition,
PrefixDefinition,
UnitDefinition,
)
from pint.errors import DefinitionSyntaxError
from pint.testsuite import BaseTestCase
from pint.util import UnitsContainer
[docs]class TestDefinition(BaseTestCase):
def test_invalid(self):
with self.assertRaises(DefinitionSyntaxError):
Definition.from_string("x = [time] * meter")
with self.assertRaises(DefinitionSyntaxError):
Definition.from_string("[x] = [time] * meter")
def test_prefix_definition(self):
self.assertRaises(ValueError, Definition.from_string, "m- = 1e-3 k")
for definition in ("m- = 1e-3", "m- = 10**-3", "m- = 0.001"):
x = Definition.from_string(definition)
self.assertIsInstance(x, PrefixDefinition)
self.assertEqual(x.name, "m")
self.assertEqual(x.aliases, ())
self.assertEqual(x.converter.to_reference(1000), 1)
self.assertEqual(x.converter.from_reference(0.001), 1)
self.assertEqual(str(x), "m")
x = Definition.from_string("kilo- = 1e-3 = k-")
self.assertIsInstance(x, PrefixDefinition)
self.assertEqual(x.name, "kilo")
self.assertEqual(x.aliases, ())
self.assertEqual(x.symbol, "k")
self.assertEqual(x.converter.to_reference(1000), 1)
self.assertEqual(x.converter.from_reference(0.001), 1)
x = Definition.from_string("kilo- = 1e-3 = k- = anotherk-")
self.assertIsInstance(x, PrefixDefinition)
self.assertEqual(x.name, "kilo")
self.assertEqual(x.aliases, ("anotherk",))
self.assertEqual(x.symbol, "k")
self.assertEqual(x.converter.to_reference(1000), 1)
self.assertEqual(x.converter.from_reference(0.001), 1)
def test_baseunit_definition(self):
x = Definition.from_string("meter = [length]")
self.assertIsInstance(x, UnitDefinition)
self.assertTrue(x.is_base)
self.assertEqual(x.reference, UnitsContainer({"[length]": 1}))
def test_unit_definition(self):
x = Definition.from_string("coulomb = ampere * second")
self.assertIsInstance(x, UnitDefinition)
self.assertFalse(x.is_base)
self.assertIsInstance(x.converter, ScaleConverter)
self.assertEqual(x.converter.scale, 1)
self.assertEqual(x.reference, UnitsContainer(ampere=1, second=1))
x = Definition.from_string("faraday = 96485.3399 * coulomb")
self.assertIsInstance(x, UnitDefinition)
self.assertFalse(x.is_base)
self.assertIsInstance(x.converter, ScaleConverter)
self.assertEqual(x.converter.scale, 96485.3399)
self.assertEqual(x.reference, UnitsContainer(coulomb=1))
x = Definition.from_string("degF = 9 / 5 * kelvin; offset: 255.372222")
self.assertIsInstance(x, UnitDefinition)
self.assertFalse(x.is_base)
self.assertIsInstance(x.converter, OffsetConverter)
self.assertEqual(x.converter.scale, 9 / 5)
self.assertEqual(x.converter.offset, 255.372222)
self.assertEqual(x.reference, UnitsContainer(kelvin=1))
x = Definition.from_string(
"turn = 6.28 * radian = _ = revolution = = cycle = _"
)
self.assertIsInstance(x, UnitDefinition)
self.assertEqual(x.name, "turn")
self.assertEqual(x.aliases, ("revolution", "cycle"))
self.assertEqual(x.symbol, "turn")
self.assertFalse(x.is_base)
self.assertIsInstance(x.converter, ScaleConverter)
self.assertEqual(x.converter.scale, 6.28)
self.assertEqual(x.reference, UnitsContainer(radian=1))
self.assertRaises(
ValueError,
Definition.from_string,
"degF = 9 / 5 * kelvin; offset: 255.372222 bla",
)
def test_dimension_definition(self):
x = DimensionDefinition("[time]", "", (), converter="")
self.assertTrue(x.is_base)
self.assertEqual(x.name, "[time]")
x = Definition.from_string("[speed] = [length]/[time]")
self.assertIsInstance(x, DimensionDefinition)
self.assertEqual(x.reference, UnitsContainer({"[length]": 1, "[time]": -1}))
def test_alias_definition(self):
x = Definition.from_string("@alias meter = metro = metr")
self.assertIsInstance(x, AliasDefinition)
self.assertEqual(x.name, "meter")
self.assertEqual(x.aliases, ("metro", "metr"))