d9ebec7b70
generate/rate_comprehension/units.py: BaseUnit + RateUnit (numerator/denominator) + the three single-rate compositions — rate_times_time (mile/hour × hour = mile; refuses mile/hour × minute), rate_from_quantity_over_time (mile ÷ hour = mile/hour), time_from_quantity_over_rate (mile ÷ mile/hour = hour; refuses dollar ÷ mile/hour). A non-composing op raises UnitError (the wrong=0 dimensional gate), never fabricates a unit. Deliberately tiny: bare-name units, no generic dimensional universe, no semantic unit-class typing, no unit conversion, no compound-of-compound. Fresh off-serving organ (generate/rate_comprehension/). 10 tests incl. all three refusals + consistent composition.
76 lines
2.4 KiB
Python
76 lines
2.4 KiB
Python
"""Tests for the R3 compound-unit algebra (R3a).
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Pins the three single-rate compositions and — load-bearing — that a non-composing operation
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REFUSES (``UnitError``) rather than fabricating a unit. The dimensional check is the wrong=0 gate.
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"""
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from __future__ import annotations
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import dataclasses
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import pytest
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from generate.rate_comprehension.units import (
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BaseUnit,
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RateUnit,
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UnitError,
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rate_from_quantity_over_time,
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rate_times_time,
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time_from_quantity_over_rate,
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)
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_MPH = RateUnit("mile", "hour")
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def test_rate_times_time_composes() -> None:
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assert rate_times_time(_MPH, BaseUnit("hour")) == BaseUnit("mile")
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def test_rate_times_wrong_time_refuses() -> None:
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# mile/hour × minute — the time unit is not the rate's denominator.
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with pytest.raises(UnitError):
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rate_times_time(_MPH, BaseUnit("minute"))
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# students/hour × mile.
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with pytest.raises(UnitError):
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rate_times_time(RateUnit("student", "hour"), BaseUnit("mile"))
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def test_quantity_over_time_makes_rate() -> None:
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assert rate_from_quantity_over_time(BaseUnit("mile"), BaseUnit("hour")) == _MPH
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def test_quantity_over_same_unit_refuses() -> None:
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with pytest.raises(UnitError):
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rate_from_quantity_over_time(BaseUnit("mile"), BaseUnit("mile"))
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def test_quantity_over_rate_makes_time() -> None:
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assert time_from_quantity_over_rate(BaseUnit("mile"), _MPH) == BaseUnit("hour")
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def test_quantity_over_rate_wrong_numerator_refuses() -> None:
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# dollar ÷ mile/hour — the quantity unit is not the rate's numerator.
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with pytest.raises(UnitError):
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time_from_quantity_over_rate(BaseUnit("dollar"), _MPH)
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def test_rate_unit_numerator_equals_denominator_refuses() -> None:
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with pytest.raises(UnitError):
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RateUnit("mile", "mile")
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def test_three_operations_compose_consistently() -> None:
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# mile/hour × hour = mile; mile ÷ hour = mile/hour; mile ÷ mile/hour = hour.
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quantity = rate_times_time(_MPH, BaseUnit("hour"))
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assert rate_from_quantity_over_time(quantity, BaseUnit("hour")) == _MPH
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assert time_from_quantity_over_rate(quantity, _MPH) == BaseUnit("hour")
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def test_units_are_frozen() -> None:
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with pytest.raises(dataclasses.FrozenInstanceError):
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_MPH.numerator = "kilometer" # type: ignore[misc]
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def test_empty_unit_name_refuses() -> None:
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with pytest.raises(UnitError):
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BaseUnit("")
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