import copy
import functools
import logging
import math
import re

import pytest

from pint import (
    DefinitionSyntaxError,
    DimensionalityError,
    RedefinitionError,
    UndefinedUnitError,
)
from pint.compat import np
from pint.registry import LazyRegistry, UnitRegistry
from pint.testsuite import QuantityTestCase, helpers
from pint.util import ParserHelper, UnitsContainer


class TestUnit(QuantityTestCase):
    def test_creation(self):
        for arg in ("meter", UnitsContainer(meter=1), self.U_("m")):
            assert self.U_(arg)._units == UnitsContainer(meter=1)
        with pytest.raises(TypeError):
            self.U_(1)

    def test_deepcopy(self):
        x = self.U_(UnitsContainer(meter=1))
        assert x == copy.deepcopy(x)

    def test_unit_repr(self):
        x = self.U_(UnitsContainer(meter=1))
        assert str(x) == "meter"
        assert repr(x) == "<Unit('meter')>"

    def test_unit_formatting(self, subtests):
        x = self.U_(UnitsContainer(meter=2, kilogram=1, second=-1))
        for spec, result in (
            ("{}", str(x)),
            ("{!s}", str(x)),
            ("{!r}", repr(x)),
            (
                "{:L}",
                r"\frac{\mathrm{kilogram} \cdot \mathrm{meter}^{2}}{\mathrm{second}}",
            ),
            ("{:P}", "kilogram·meter²/second"),
            ("{:H}", "kilogram meter<sup>2</sup>/second"),
            ("{:C}", "kilogram*meter**2/second"),
            ("{:Lx}", r"\si[]{\kilo\gram\meter\squared\per\second}"),
            ("{:~}", "kg * m ** 2 / s"),
            ("{:L~}", r"\frac{\mathrm{kg} \cdot \mathrm{m}^{2}}{\mathrm{s}}"),
            ("{:P~}", "kg·m²/s"),
            ("{:H~}", "kg m<sup>2</sup>/s"),
            ("{:C~}", "kg*m**2/s"),
        ):
            with subtests.test(spec):
                assert spec.format(x) == result

    def test_unit_default_formatting(self, subtests):
        ureg = UnitRegistry()
        x = ureg.Unit(UnitsContainer(meter=2, kilogram=1, second=-1))
        for spec, result in (
            (
                "L",
                r"\frac{\mathrm{kilogram} \cdot \mathrm{meter}^{2}}{\mathrm{second}}",
            ),
            ("P", "kilogram·meter²/second"),
            ("H", "kilogram meter<sup>2</sup>/second"),
            ("C", "kilogram*meter**2/second"),
            ("~", "kg * m ** 2 / s"),
            ("L~", r"\frac{\mathrm{kg} \cdot \mathrm{m}^{2}}{\mathrm{s}}"),
            ("P~", "kg·m²/s"),
            ("H~", "kg m<sup>2</sup>/s"),
            ("C~", "kg*m**2/s"),
        ):
            with subtests.test(spec):
                ureg.default_format = spec
                assert f"{x}" == result, f"Failed for {spec}, {result}"

    def test_unit_formatting_snake_case(self, subtests):
        # Test that snake_case units are escaped where appropriate
        ureg = UnitRegistry()
        x = ureg.Unit(UnitsContainer(oil_barrel=1))
        for spec, result in (
            ("L", r"\mathrm{oil\_barrel}"),
            ("P", "oil_barrel"),
            ("H", "oil_barrel"),
            ("C", "oil_barrel"),
            ("~", "oil_bbl"),
            ("L~", r"\mathrm{oil\_bbl}"),
            ("P~", "oil_bbl"),
            ("H~", "oil_bbl"),
            ("C~", "oil_bbl"),
        ):
            with subtests.test(spec):
                ureg.default_format = spec
                assert f"{x}" == result, f"Failed for {spec}, {result}"

    def test_unit_formatting_custom(self, monkeypatch):
        from pint import formatting, register_unit_format

        monkeypatch.setattr(formatting, "_FORMATTERS", formatting._FORMATTERS.copy())

        @register_unit_format("new")
        def format_new(unit, **options):
            return "new format"

        ureg = UnitRegistry()

        assert "{:new}".format(ureg.m) == "new format"

    def test_ipython(self):
        alltext = []

        class Pretty:
            @staticmethod
            def text(text):
                alltext.append(text)

        ureg = UnitRegistry()
        x = ureg.Unit(UnitsContainer(meter=2, kilogram=1, second=-1))
        assert x._repr_html_() == "kilogram meter<sup>2</sup>/second"
        assert (
            x._repr_latex_() == r"$\frac{\mathrm{kilogram} \cdot "
            r"\mathrm{meter}^{2}}{\mathrm{second}}$"
        )
        x._repr_pretty_(Pretty, False)
        assert "".join(alltext) == "kilogram·meter²/second"
        ureg.default_format = "~"
        assert x._repr_html_() == "kg m<sup>2</sup>/s"
        assert (
            x._repr_latex_() == r"$\frac{\mathrm{kg} \cdot \mathrm{m}^{2}}{\mathrm{s}}$"
        )
        alltext = []
        x._repr_pretty_(Pretty, False)
        assert "".join(alltext) == "kg·m²/s"

    def test_unit_mul(self):
        x = self.U_("m")
        assert x * 1 == self.Q_(1, "m")
        assert x * 0.5 == self.Q_(0.5, "m")
        assert x * self.Q_(1, "m") == self.Q_(1, "m**2")
        assert 1 * x == self.Q_(1, "m")

    def test_unit_div(self):
        x = self.U_("m")
        assert x / 1 == self.Q_(1, "m")
        assert x / 0.5 == self.Q_(2.0, "m")
        assert x / self.Q_(1, "m") == self.Q_(1)

    def test_unit_rdiv(self):
        x = self.U_("m")
        assert 1 / x == self.Q_(1, "1/m")

    def test_unit_pow(self):
        x = self.U_("m")
        assert x ** 2 == self.U_("m**2")

    def test_unit_hash(self):
        x = self.U_("m")
        assert hash(x) == hash(x._units)

    def test_unit_eqs(self):
        x = self.U_("m")
        assert x == self.U_("m")
        assert x != self.U_("cm")

        assert x == self.Q_(1, "m")
        assert x != self.Q_(2, "m")

        assert x == UnitsContainer({"meter": 1})

        y = self.U_("cm/m")
        assert y == 0.01

        assert self.U_("byte") == self.U_("byte")
        assert not (self.U_("byte") != self.U_("byte"))

    def test_unit_cmp(self):

        x = self.U_("m")
        assert x < self.U_("km")
        assert x > self.U_("mm")

        y = self.U_("m/mm")
        assert y > 1
        assert y < 1e6

    def test_dimensionality(self):

        x = self.U_("m")
        assert x.dimensionality == UnitsContainer({"[length]": 1})

    def test_dimensionless(self):

        assert self.U_("m/mm").dimensionless
        assert not self.U_("m").dimensionless

    def test_unit_casting(self):

        assert int(self.U_("m/mm")) == 1000
        assert float(self.U_("mm/m")) == 1e-3
        assert complex(self.U_("mm/mm")) == 1 + 0j

    @helpers.requires_numpy
    def test_array_interface(self):
        import numpy as np

        x = self.U_("m")
        arr = np.ones(10)
        helpers.assert_quantity_equal(arr * x, self.Q_(arr, "m"))
        helpers.assert_quantity_equal(arr / x, self.Q_(arr, "1/m"))
        helpers.assert_quantity_equal(x / arr, self.Q_(arr, "m"))


class TestRegistry(QuantityTestCase):
    @classmethod
    def setup_class(cls):
        super().setup_class()
        cls.ureg.autoconvert_offset_to_baseunit = False

    def test_base(self):
        ureg = UnitRegistry(None)
        ureg.define("meter = [length]")
        with pytest.raises(DefinitionSyntaxError):
            ureg.define("meter = [length]")
        with pytest.raises(TypeError):
            ureg.define(list())
        ureg.define("degC = kelvin; offset: 273.15")

    def test_define(self):
        ureg = UnitRegistry(None)
        assert isinstance(dir(ureg), list)
        assert len(dir(ureg)) > 0

    def test_load(self):
        import pkg_resources

        from pint import unit

        data = pkg_resources.resource_filename(unit.__name__, "default_en.txt")
        ureg1 = UnitRegistry()
        ureg2 = UnitRegistry(data)
        assert dir(ureg1) == dir(ureg2)
        with pytest.raises(ValueError):
            UnitRegistry(None).load_definitions("notexisting")

    def test_default_format(self):
        ureg = UnitRegistry()
        q = ureg.meter
        s1 = f"{q}"
        s2 = f"{q:~}"
        ureg.default_format = "~"
        s3 = f"{q}"
        assert s2 == s3
        assert s1 != s3
        assert ureg.default_format == "~"

    def test_iterate(self):
        ureg = UnitRegistry()
        assert "meter" in list(ureg)

    def test_parse_number(self):
        assert self.ureg.parse_expression("pi") == math.pi
        assert self.ureg.parse_expression("x", x=2) == 2
        assert self.ureg.parse_expression("x", x=2.3) == 2.3
        assert self.ureg.parse_expression("x * y", x=2.3, y=3) == 2.3 * 3
        assert self.ureg.parse_expression("x", x=(1 + 1j)) == (1 + 1j)

    def test_parse_single(self):
        assert self.ureg.parse_expression("meter") == self.Q_(
            1, UnitsContainer(meter=1.0)
        )
        assert self.ureg.parse_expression("second") == self.Q_(
            1, UnitsContainer(second=1.0)
        )

    def test_parse_alias(self):
        assert self.ureg.parse_expression("metre") == self.Q_(
            1, UnitsContainer(meter=1.0)
        )

    def test_parse_plural(self):
        assert self.ureg.parse_expression("meters") == self.Q_(
            1, UnitsContainer(meter=1.0)
        )

    def test_parse_prefix(self):
        assert self.ureg.parse_expression("kilometer") == self.Q_(
            1, UnitsContainer(kilometer=1.0)
        )

    def test_parse_complex(self):
        assert self.ureg.parse_expression("kilometre") == self.Q_(
            1, UnitsContainer(kilometer=1.0)
        )
        assert self.ureg.parse_expression("kilometres") == self.Q_(
            1, UnitsContainer(kilometer=1.0)
        )

    def test_parse_mul_div(self):
        assert self.ureg.parse_expression("meter*meter") == self.Q_(
            1, UnitsContainer(meter=2.0)
        )
        assert self.ureg.parse_expression("meter**2") == self.Q_(
            1, UnitsContainer(meter=2.0)
        )
        assert self.ureg.parse_expression("meter*second") == self.Q_(
            1, UnitsContainer(meter=1.0, second=1)
        )
        assert self.ureg.parse_expression("meter/second") == self.Q_(
            1, UnitsContainer(meter=1.0, second=-1)
        )
        assert self.ureg.parse_expression("meter/second**2") == self.Q_(
            1, UnitsContainer(meter=1.0, second=-2)
        )

    def test_parse_pretty(self):
        assert self.ureg.parse_expression("meter/second²") == self.Q_(
            1, UnitsContainer(meter=1.0, second=-2)
        )
        assert self.ureg.parse_expression("m³/s³") == self.Q_(
            1, UnitsContainer(meter=3.0, second=-3)
        )
        assert self.ureg.parse_expression("meter² · second") == self.Q_(
            1, UnitsContainer(meter=2.0, second=1)
        )
        assert self.ureg.parse_expression("m²·s⁻²") == self.Q_(
            1, UnitsContainer(meter=2, second=-2)
        )
        assert self.ureg.parse_expression("meter⁰.⁵·second") == self.Q_(
            1, UnitsContainer(meter=0.5, second=1)
        )
        assert self.ureg.parse_expression("meter³⁷/second⁴.³²¹") == self.Q_(
            1, UnitsContainer(meter=37, second=-4.321)
        )

    def test_parse_factor(self):
        assert self.ureg.parse_expression("42*meter") == self.Q_(
            42, UnitsContainer(meter=1.0)
        )
        assert self.ureg.parse_expression("meter*42") == self.Q_(
            42, UnitsContainer(meter=1.0)
        )

    def test_rep_and_parse(self):
        q = self.Q_(1, "g/(m**2*s)")
        assert self.Q_(q.magnitude, str(q.units)) == q

    def test_as_delta(self):
        parse = self.ureg.parse_units
        assert parse("kelvin", as_delta=True) == UnitsContainer(kelvin=1)
        assert parse("kelvin", as_delta=False) == UnitsContainer(kelvin=1)
        assert parse("kelvin**(-1)", as_delta=True) == UnitsContainer(kelvin=-1)
        assert parse("kelvin**(-1)", as_delta=False) == UnitsContainer(kelvin=-1)
        assert parse("kelvin**2", as_delta=True) == UnitsContainer(kelvin=2)
        assert parse("kelvin**2", as_delta=False) == UnitsContainer(kelvin=2)
        assert parse("kelvin*meter", as_delta=True) == UnitsContainer(kelvin=1, meter=1)
        assert parse("kelvin*meter", as_delta=False) == UnitsContainer(
            kelvin=1, meter=1
        )

    @helpers.requires_numpy
    def test_parse_with_force_ndarray(self):
        ureg = UnitRegistry(force_ndarray=True)

        assert ureg.parse_expression("m * s ** -2").units == ureg.m / ureg.s ** 2

    def test_parse_expression_with_preprocessor(self):
        # Add parsing of UDUNITS-style power
        self.ureg.preprocessors.append(
            functools.partial(
                re.sub,
                r"(?<=[A-Za-z])(?![A-Za-z])(?<![0-9\-][eE])(?<![0-9\-])(?=[0-9\-])",
                "**",
            )
        )
        # Test equality
        assert self.ureg.parse_expression("42 m2") == self.Q_(
            42, UnitsContainer(meter=2.0)
        )
        assert self.ureg.parse_expression("1e6 Hz s-2") == self.Q_(
            1e6, UnitsContainer(second=-3.0)
        )
        assert self.ureg.parse_expression("3 metre3") == self.Q_(
            3, UnitsContainer(meter=3.0)
        )
        # Clean up and test previously expected value
        self.ureg.preprocessors.pop()
        assert self.ureg.parse_expression("1e6 Hz s-2") == self.Q_(
            999998.0, UnitsContainer()
        )

    def test_parse_unit_with_preprocessor(self):
        # Add parsing of UDUNITS-style power
        self.ureg.preprocessors.append(
            functools.partial(
                re.sub,
                r"(?<=[A-Za-z])(?![A-Za-z])(?<![0-9\-][eE])(?<![0-9\-])(?=[0-9\-])",
                "**",
            )
        )
        # Test equality
        assert self.ureg.parse_units("m2") == UnitsContainer(meter=2.0)
        assert self.ureg.parse_units("m-2") == UnitsContainer(meter=-2.0)
        # Clean up
        self.ureg.preprocessors.pop()

    def test_name(self):
        with pytest.raises(UndefinedUnitError):
            self.ureg.get_name("asdf")

    def test_symbol(self):
        with pytest.raises(UndefinedUnitError):
            self.ureg.get_symbol("asdf")

        assert self.ureg.get_symbol("meter") == "m"
        assert self.ureg.get_symbol("second") == "s"
        assert self.ureg.get_symbol("hertz") == "Hz"

        assert self.ureg.get_symbol("kilometer") == "km"
        assert self.ureg.get_symbol("megahertz") == "MHz"
        assert self.ureg.get_symbol("millisecond") == "ms"

    def test_imperial_symbol(self):
        assert self.ureg.get_symbol("inch") == "in"
        assert self.ureg.get_symbol("foot") == "ft"
        assert self.ureg.get_symbol("inches") == "in"
        assert self.ureg.get_symbol("feet") == "ft"
        assert self.ureg.get_symbol("international_foot") == "ft"
        assert self.ureg.get_symbol("international_inch") == "in"

    def test_pint(self):
        assert self.ureg.pint < self.ureg.liter
        assert self.ureg.pint < self.ureg.imperial_pint

    def test_wraps(self):
        def func(x):
            return x

        ureg = self.ureg

        with pytest.raises(TypeError):
            ureg.wraps((3 * ureg.meter, [None]))
        with pytest.raises(TypeError):
            ureg.wraps((None, [3 * ureg.meter]))

        f0 = ureg.wraps(None, [None])(func)
        assert f0(3.0) == 3.0

        f0 = ureg.wraps(None, None)(func)
        assert f0(3.0) == 3.0

        f1 = ureg.wraps(None, ["meter"])(func)
        with pytest.raises(ValueError):
            f1(3.0)
        assert f1(3.0 * ureg.centimeter) == 0.03
        assert f1(3.0 * ureg.meter) == 3.0
        with pytest.raises(DimensionalityError):
            f1(3 * ureg.second)

        f1b = ureg.wraps(None, [ureg.meter])(func)
        with pytest.raises(ValueError):
            f1b(3.0)
        assert f1b(3.0 * ureg.centimeter) == 0.03
        assert f1b(3.0 * ureg.meter) == 3.0
        with pytest.raises(DimensionalityError):
            f1b(3 * ureg.second)

        f1c = ureg.wraps("meter", [ureg.meter])(func)
        assert f1c(3.0 * ureg.centimeter) == 0.03 * ureg.meter
        assert f1c(3.0 * ureg.meter) == 3.0 * ureg.meter
        with pytest.raises(DimensionalityError):
            f1c(3 * ureg.second)

        f1d = ureg.wraps(ureg.meter, [ureg.meter])(func)
        assert f1d(3.0 * ureg.centimeter) == 0.03 * ureg.meter
        assert f1d(3.0 * ureg.meter) == 3.0 * ureg.meter
        with pytest.raises(DimensionalityError):
            f1d(3 * ureg.second)

        f1 = ureg.wraps(None, "meter")(func)
        with pytest.raises(ValueError):
            f1(3.0)
        assert f1(3.0 * ureg.centimeter) == 0.03
        assert f1(3.0 * ureg.meter) == 3.0
        with pytest.raises(DimensionalityError):
            f1(3 * ureg.second)

        f2 = ureg.wraps("centimeter", ["meter"])(func)
        with pytest.raises(ValueError):
            f2(3.0)
        assert f2(3.0 * ureg.centimeter) == 0.03 * ureg.centimeter
        assert f2(3.0 * ureg.meter) == 3 * ureg.centimeter

        f3 = ureg.wraps("centimeter", ["meter"], strict=False)(func)
        assert f3(3) == 3 * ureg.centimeter
        assert f3(3.0 * ureg.centimeter) == 0.03 * ureg.centimeter
        assert f3(3.0 * ureg.meter) == 3.0 * ureg.centimeter

        def gfunc(x, y):
            return x + y

        g0 = ureg.wraps(None, [None, None])(gfunc)
        assert g0(3, 1) == 4

        g1 = ureg.wraps(None, ["meter", "centimeter"])(gfunc)
        with pytest.raises(ValueError):
            g1(3 * ureg.meter, 1)
        assert g1(3 * ureg.meter, 1 * ureg.centimeter) == 4
        assert g1(3 * ureg.meter, 1 * ureg.meter) == 3 + 100

        def hfunc(x, y):
            return x, y

        h0 = ureg.wraps(None, [None, None])(hfunc)
        assert h0(3, 1) == (3, 1)

        h1 = ureg.wraps(["meter", "centimeter"], [None, None])(hfunc)
        assert h1(3, 1) == [3 * ureg.meter, 1 * ureg.cm]

        h2 = ureg.wraps(("meter", "centimeter"), [None, None])(hfunc)
        assert h2(3, 1) == (3 * ureg.meter, 1 * ureg.cm)

        h3 = ureg.wraps((None,), (None, None))(hfunc)
        assert h3(3, 1) == (3, 1)

    def test_wrap_referencing(self):

        ureg = self.ureg

        def gfunc(x, y):
            return x + y

        def gfunc2(x, y):
            return x ** 2 + y

        def gfunc3(x, y):
            return x ** 2 * y

        rst = 3.0 * ureg.meter + 1.0 * ureg.centimeter

        g0 = ureg.wraps("=A", ["=A", "=A"])(gfunc)
        assert g0(3.0 * ureg.meter, 1.0 * ureg.centimeter) == rst.to("meter")
        assert g0(3, 1) == 4

        g1 = ureg.wraps("=A", ["=A", "=A"])(gfunc)
        assert g1(3.0 * ureg.meter, 1.0 * ureg.centimeter) == rst.to("centimeter")

        g2 = ureg.wraps("=A", ["=A", "=A"])(gfunc)
        assert g2(3.0 * ureg.meter, 1.0 * ureg.centimeter) == rst.to("meter")

        g3 = ureg.wraps("=A**2", ["=A", "=A**2"])(gfunc2)
        a = 3.0 * ureg.meter
        b = (2.0 * ureg.centimeter) ** 2
        assert g3(a, b) == gfunc2(a, b)
        assert g3(3, 2) == gfunc2(3, 2)

        g4 = ureg.wraps("=A**2 * B", ["=A", "=B"])(gfunc3)
        assert g4(3.0 * ureg.meter, 2.0 * ureg.second) == ureg(
            "(3*meter)**2 * 2 *second"
        )
        assert g4(3.0 * ureg.meter, 2.0) == ureg("(3*meter)**2 * 2")
        assert g4(3.0, 2.0 * ureg.second) == ureg("3**2 * 2 * second")

    def test_check(self):
        def func(x):
            return x

        ureg = self.ureg

        f0 = ureg.check("[length]")(func)
        with pytest.raises(DimensionalityError):
            f0(3.0)
        assert f0(3.0 * ureg.centimeter) == 0.03 * ureg.meter
        with pytest.raises(DimensionalityError):
            f0(3.0 * ureg.kilogram)

        f0b = ureg.check(ureg.meter)(func)
        with pytest.raises(DimensionalityError):
            f0b(3.0)
        assert f0b(3.0 * ureg.centimeter) == 0.03 * ureg.meter
        with pytest.raises(DimensionalityError):
            f0b(3.0 * ureg.kilogram)

        def gfunc(x, y):
            return x / y

        g0 = ureg.check(None, None)(gfunc)
        assert g0(6, 2) == 3
        assert g0(6 * ureg.parsec, 2) == 3 * ureg.parsec

        g1 = ureg.check("[speed]", "[time]")(gfunc)
        with pytest.raises(DimensionalityError):
            g1(3.0, 1)
        with pytest.raises(DimensionalityError):
            g1(1 * ureg.parsec, 1 * ureg.angstrom)
        with pytest.raises(TypeError):
            g1(1 * ureg.km / ureg.hour, 1 * ureg.hour, 3.0)
        assert (
            g1(3.6 * ureg.km / ureg.hour, 1 * ureg.second)
            == 1 * ureg.meter / ureg.second ** 2
        )

        with pytest.raises(TypeError):
            ureg.check("[speed]")(gfunc)
        with pytest.raises(TypeError):
            ureg.check("[speed]", "[time]", "[mass]")(gfunc)

    def test_to_ref_vs_to(self):
        self.ureg.autoconvert_offset_to_baseunit = True
        q = 8.0 * self.ureg.inch
        t = 8.0 * self.ureg.degF
        dt = 8.0 * self.ureg.delta_degF
        assert q.to("yard").magnitude == self.ureg._units[
            "inch"
        ].converter.to_reference(8.0)
        assert t.to("kelvin").magnitude == self.ureg._units[
            "degF"
        ].converter.to_reference(8.0)
        assert dt.to("kelvin").magnitude == self.ureg._units[
            "delta_degF"
        ].converter.to_reference(8.0)

    def test_redefinition(self, caplog):
        d = UnitRegistry().define

        with caplog.at_level(logging.DEBUG):
            d("meter = [fruits]")
            d("kilo- = 1000")
            d("[speed] = [vegetables]")

            # aliases
            d("bla = 3.2 meter = inch")
            d("myk- = 1000 = kilo-")

        assert len(caplog.records) == 5

    def test_convert_parse_str(self):
        ureg = self.ureg
        assert ureg.convert(1, "meter", "inch") == ureg.convert(
            1, UnitsContainer(meter=1), UnitsContainer(inch=1)
        )

    @helpers.requires_numpy
    def test_convert_inplace(self):
        ureg = self.ureg

        # Conversions with single units take a different codepath than
        # Conversions with more than one unit.
        src_dst1 = UnitsContainer(meter=1), UnitsContainer(inch=1)
        src_dst2 = UnitsContainer(meter=1, second=-1), UnitsContainer(inch=1, minute=-1)
        for src, dst in (src_dst1, src_dst2):
            v = (ureg.convert(1, src, dst),)

            a = np.ones((3, 1))
            ac = np.ones((3, 1))

            r1 = ureg.convert(a, src, dst)
            np.testing.assert_allclose(r1, v * ac)
            assert r1 is not a

            r2 = ureg.convert(a, src, dst, inplace=True)
            np.testing.assert_allclose(r2, v * ac)
            assert r2 is a

    def test_repeated_convert(self):
        # Because of caching, repeated conversions were failing.
        self.ureg.convert(1, "m", "ft")
        self.ureg.convert(1, "m", "ft")

    def test_singular_SI_prefix_convert(self):
        # Fix for issue 156
        self.ureg.convert(1, "mm", "m")
        self.ureg.convert(1, "ms", "s")
        self.ureg.convert(1, "m", "mm")
        self.ureg.convert(1, "s", "ms")

    def test_parse_units(self):
        ureg = self.ureg
        assert ureg.parse_units("") == ureg.Unit("")
        with pytest.raises(ValueError):
            ureg.parse_units("2 * meter")

    def test_parse_string_pattern(self):
        ureg = self.ureg
        assert ureg.parse_pattern("10'11", r"{foot}'{inch}") == [
            ureg.Quantity(10.0, "foot"),
            ureg.Quantity(11.0, "inch"),
        ]

    def test_parse_string_pattern_no_preprocess(self):
        """Were preprocessors enabled, this would be interpreted as 10*11, not
        two separate units, and thus cause the parsing to fail"""
        ureg = self.ureg
        assert ureg.parse_pattern("10 11", r"{kg} {lb}") == [
            ureg.Quantity(10.0, "kilogram"),
            ureg.Quantity(11.0, "pound"),
        ]

    def test_parse_pattern_many_results(self):
        ureg = self.ureg
        assert ureg.parse_pattern(
            "1.5kg or 2kg will be fine, if you do not have 3kg",
            r"{kg}kg",
            many=True,
        ) == [
            [ureg.Quantity(1.5, "kilogram")],
            [ureg.Quantity(2.0, "kilogram")],
            [ureg.Quantity(3.0, "kilogram")],
        ]

    def test_parse_pattern_many_results_two_units(self):
        ureg = self.ureg
        assert ureg.parse_pattern("10'10 or 10'11", "{foot}'{inch}", many=True) == [
            [ureg.Quantity(10.0, "foot"), ureg.Quantity(10.0, "inch")],
            [ureg.Quantity(10.0, "foot"), ureg.Quantity(11.0, "inch")],
        ]

    def test_case_sensitivity(self):
        ureg = self.ureg
        # Default
        with pytest.raises(UndefinedUnitError):
            ureg.parse_units("Meter")
        with pytest.raises(UndefinedUnitError):
            ureg.parse_units("j")
        # Force True
        with pytest.raises(UndefinedUnitError):
            ureg.parse_units("Meter", case_sensitive=True)
        with pytest.raises(UndefinedUnitError):
            ureg.parse_units("j", case_sensitive=True)
        # Force False
        assert ureg.parse_units("Meter", case_sensitive=False) == UnitsContainer(
            meter=1
        )
        assert ureg.parse_units("j", case_sensitive=False) == UnitsContainer(joule=1)


class TestCaseInsensitiveRegistry(QuantityTestCase):

    kwargs = dict(case_sensitive=False)

    def test_case_sensitivity(self):
        ureg = self.ureg
        # Default
        assert ureg.parse_units("Meter") == UnitsContainer(meter=1)
        assert ureg.parse_units("j") == UnitsContainer(joule=1)
        # Force True
        with pytest.raises(UndefinedUnitError):
            ureg.parse_units("Meter", case_sensitive=True)
        with pytest.raises(UndefinedUnitError):
            ureg.parse_units("j", case_sensitive=True)
        # Force False
        assert ureg.parse_units("Meter", case_sensitive=False) == UnitsContainer(
            meter=1
        )
        assert ureg.parse_units("j", case_sensitive=False) == UnitsContainer(joule=1)


class TestCompatibleUnits(QuantityTestCase):
    def _test(self, input_units):
        gd = self.ureg.get_dimensionality
        dim = gd(input_units)
        equiv = self.ureg.get_compatible_units(input_units)
        for eq in equiv:
            assert gd(eq) == dim
        assert equiv == self.ureg.get_compatible_units(dim)

    def _test2(self, units1, units2):
        equiv1 = self.ureg.get_compatible_units(units1)
        equiv2 = self.ureg.get_compatible_units(units2)
        assert equiv1 == equiv2

    def test_many(self):
        self._test(self.ureg.meter)
        self._test(self.ureg.seconds)
        self._test(self.ureg.newton)
        self._test(self.ureg.kelvin)

    def test_context_sp(self):

        gd = self.ureg.get_dimensionality

        # length, frequency, energy
        valid = [
            gd(self.ureg.meter),
            gd(self.ureg.hertz),
            gd(self.ureg.joule),
            1 / gd(self.ureg.meter),
        ]

        with self.ureg.context("sp"):
            equiv = self.ureg.get_compatible_units(self.ureg.meter)
            result = set()
            for eq in equiv:
                dim = gd(eq)
                result.add(dim)
                assert dim in valid

            assert len(result) == len(valid)

    def test_get_base_units(self):
        ureg = UnitRegistry()
        assert ureg.get_base_units("") == (1, ureg.Unit(""))
        assert ureg.get_base_units("pi") == (math.pi, ureg.Unit(""))
        assert ureg.get_base_units("ln10") == (math.log(10), ureg.Unit(""))
        assert ureg.get_base_units("meter") == ureg.get_base_units(
            ParserHelper(meter=1)
        )

    def test_get_compatible_units(self):
        ureg = UnitRegistry()
        assert ureg.get_compatible_units("") == frozenset()
        assert ureg.get_compatible_units("meter") == ureg.get_compatible_units(
            ParserHelper(meter=1)
        )


class TestRegistryWithDefaultRegistry(TestRegistry):
    @classmethod
    def setup_class(cls):
        from pint import _DEFAULT_REGISTRY

        cls.ureg = _DEFAULT_REGISTRY
        cls.Q_ = cls.ureg.Quantity

    def test_lazy(self):
        x = LazyRegistry()
        x.test = "test"
        assert isinstance(x, UnitRegistry)
        y = LazyRegistry()
        y("meter")
        assert isinstance(y, UnitRegistry)

    def test_redefinition(self):
        d = self.ureg.define
        with pytest.raises(DefinitionSyntaxError):
            d("meter = [time]")
        with pytest.raises(RedefinitionError):
            d("meter = [newdim]")
        with pytest.raises(RedefinitionError):
            d("kilo- = 1000")
        with pytest.raises(RedefinitionError):
            d("[speed] = [length]")

        # aliases
        assert "inch" in self.ureg._units
        with pytest.raises(RedefinitionError):
            d("bla = 3.2 meter = inch")
        with pytest.raises(RedefinitionError):
            d("myk- = 1000 = kilo-")


class TestConvertWithOffset(QuantityTestCase):

    # The dicts in convert_with_offset are used to create a UnitsContainer.
    # We create UnitsContainer to avoid any auto-conversion of units.
    convert_with_offset = [
        (({"degC": 1}, {"degC": 1}), 10),
        (({"degC": 1}, {"kelvin": 1}), 283.15),
        (({"degC": 1}, {"degC": 1, "millimeter": 1, "meter": -1}), "error"),
        (({"degC": 1}, {"kelvin": 1, "millimeter": 1, "meter": -1}), 283150),
        (({"kelvin": 1}, {"degC": 1}), -263.15),
        (({"kelvin": 1}, {"kelvin": 1}), 10),
        (({"kelvin": 1}, {"degC": 1, "millimeter": 1, "meter": -1}), "error"),
        (({"kelvin": 1}, {"kelvin": 1, "millimeter": 1, "meter": -1}), 10000),
        (({"degC": 1, "millimeter": 1, "meter": -1}, {"degC": 1}), "error"),
        (({"degC": 1, "millimeter": 1, "meter": -1}, {"kelvin": 1}), "error"),
        (
            (
                {"degC": 1, "millimeter": 1, "meter": -1},
                {"degC": 1, "millimeter": 1, "meter": -1},
            ),
            10,
        ),
        (
            (
                {"degC": 1, "millimeter": 1, "meter": -1},
                {"kelvin": 1, "millimeter": 1, "meter": -1},
            ),
            "error",
        ),
        (({"kelvin": 1, "millimeter": 1, "meter": -1}, {"degC": 1}), -273.14),
        (({"kelvin": 1, "millimeter": 1, "meter": -1}, {"kelvin": 1}), 0.01),
        (
            (
                {"kelvin": 1, "millimeter": 1, "meter": -1},
                {"degC": 1, "millimeter": 1, "meter": -1},
            ),
            "error",
        ),
        (
            (
                {"kelvin": 1, "millimeter": 1, "meter": -1},
                {"kelvin": 1, "millimeter": 1, "meter": -1},
            ),
            10,
        ),
        (({"degC": 2}, {"kelvin": 2}), "error"),
        (({"degC": 1, "degF": 1}, {"kelvin": 2}), "error"),
        (({"degC": 1, "kelvin": 1}, {"kelvin": 2}), "error"),
    ]

    @pytest.mark.parametrize(("input_tuple", "expected"), convert_with_offset)
    def test_to_and_from_offset_units(self, input_tuple, expected):
        src, dst = input_tuple
        src, dst = UnitsContainer(src), UnitsContainer(dst)
        value = 10.0
        convert = self.ureg.convert
        if isinstance(expected, str):
            with pytest.raises(DimensionalityError):
                convert(value, src, dst)
            if src != dst:
                with pytest.raises(DimensionalityError):
                    convert(value, dst, src)
        else:
            helpers.assert_quantity_almost_equal(
                convert(value, src, dst), expected, atol=0.001
            )
            if src != dst:
                helpers.assert_quantity_almost_equal(
                    convert(expected, dst, src), value, atol=0.001
                )

    def test_alias(self):
        # Use load_definitions
        ureg = UnitRegistry(
            [
                "canonical = [] = can = alias1 = alias2\n",
                # overlapping aliases
                "@alias canonical = alias2 = alias3\n",
                # Against another alias
                "@alias alias3 = alias4\n",
            ]
        )

        # Use define
        ureg.define("@alias canonical = alias5")

        # Test that new aliases work
        # Test that pre-existing aliases and symbol are not eliminated
        for a in ("can", "alias1", "alias2", "alias3", "alias4", "alias5"):
            assert ureg.Unit(a) == ureg.Unit("canonical")

        # Test that aliases defined multiple times are not duplicated
        assert ureg._units["canonical"].aliases == (
            "alias1",
            "alias2",
            "alias3",
            "alias4",
            "alias5",
        )

        # Define against unknown name
        with pytest.raises(KeyError):
            ureg.define("@alias notexist = something")