resource-control/tests/test_basis.py

import sys
import unittest
from pathlib import Path

sys.path.insert(0, str(Path(__file__).parents[1] / "tools"))
from basis import (
    BASIS_ORDER,
    decision_grade,
    is_evidenced,
    profile,
    rank,
    resolve,
    strongest,
    validate_value,
    weakest,
)


def value(basis="measured", **overrides):
    result = {"name": "v", "basis": basis, "value": 1}
    if basis == "unknown":
        result = {"name": "v", "basis": basis, "value": None, "gap": "not measured (owner: x)"}
    result.update(overrides)
    return result


class OrderTest(unittest.TestCase):
    def test_order_runs_strongest_to_weakest(self):
        self.assertEqual("invoiced", BASIS_ORDER[0])
        self.assertEqual("unknown", BASIS_ORDER[-1])
        self.assertLess(rank("measured"), rank("estimated"))
        self.assertLess(rank("estimated"), rank("assumed"))

    def test_weakest_and_strongest_pick_opposite_ends(self):
        bases = ["measured", "assumed", "quoted"]
        self.assertEqual("assumed", weakest(bases))
        self.assertEqual("measured", strongest(bases))

    def test_empty_collection_is_unknown_not_an_error(self):
        self.assertEqual("unknown", weakest([]))

    def test_only_observed_or_contracted_bases_count_as_evidenced(self):
        for basis in ("invoiced", "measured", "quoted"):
            self.assertTrue(is_evidenced(basis))
        for basis in ("derived", "projected", "estimated", "assumed", "unknown"):
            self.assertFalse(is_evidenced(basis))

    def test_unknown_basis_name_is_rejected(self):
        with self.assertRaises(ValueError):
            rank("vibes")


class PropagationTest(unittest.TestCase):
    """A derived value is only as strong as its weakest input."""

    def test_derivation_from_measured_inputs_stays_measured(self):
        derived = value("derived", derived_from=[value("measured"), value("measured")])
        self.assertEqual("measured", resolve(derived))

    def test_one_assumed_input_drags_the_result_down(self):
        derived = value("derived", derived_from=[value("quoted"), value("assumed")])
        self.assertEqual("assumed", resolve(derived))

    def test_propagation_is_recursive(self):
        inner = value("derived", derived_from=[value("measured"), value("estimated")])
        outer = value("derived", derived_from=[value("measured"), inner])
        self.assertEqual("estimated", resolve(outer))

    def test_derived_without_inputs_is_rejected(self):
        with self.assertRaisesRegex(ValueError, "derived_from"):
            resolve(value("derived"))

    def test_non_derived_value_resolves_to_itself(self):
        self.assertEqual("quoted", resolve(value("quoted")))


class ValidationTest(unittest.TestCase):
    def test_unknown_must_not_carry_a_quantity(self):
        with self.assertRaises(ValueError):
            validate_value({"basis": "unknown", "value": 0, "gap": "g"})

    def test_unknown_must_name_the_gap_and_owner(self):
        with self.assertRaisesRegex(ValueError, "name the gap"):
            validate_value({"basis": "unknown", "value": None})

    def test_known_basis_must_carry_a_quantity(self):
        with self.assertRaisesRegex(ValueError, "must carry a quantity"):
            validate_value({"basis": "measured", "value": None})

    def test_zero_is_a_measurement_not_an_absence(self):
        validate_value({"basis": "measured", "value": 0})

    def test_derived_from_only_allowed_on_derived(self):
        with self.assertRaisesRegex(ValueError, "only a derived value"):
            validate_value(value("measured", derived_from=[value()]))

    def test_empty_proxy_target_is_rejected_but_absent_one_is_fine(self):
        with self.assertRaisesRegex(ValueError, "proxy_for"):
            validate_value(value("measured", proxy_for="  "))
        validate_value(value("measured", proxy_for=None))
        validate_value(value("measured", proxy_for="cost of the shared host"))


class DecisionGradeTest(unittest.TestCase):
    def test_all_evidenced_values_grade_evidenced(self):
        result = decision_grade([value("measured"), value("invoiced"), value("quoted")])
        self.assertEqual("evidenced", result["grade"])
        self.assertEqual(1.0, result["evidenced_ratio"])

    def test_a_single_assumption_makes_the_whole_decision_indicative(self):
        result = decision_grade([value("measured"), value("measured"), value("assumed")])
        self.assertEqual("indicative", result["grade"])
        self.assertEqual("assumed", result["weakest"])

    def test_an_unknown_makes_the_decision_insufficient(self):
        result = decision_grade([value("measured"), value("unknown")])
        self.assertEqual("insufficient", result["grade"])

    def test_precise_arithmetic_does_not_upgrade_weak_inputs(self):
        """The provider comparison: a two-decimal euro figure built on assumptions."""
        euros = value(
            "derived",
            name="labour_eur_month",
            value=60.0,
            derived_from=[value("assumed", name="hours"), value("assumed", name="rate")],
        )
        result = decision_grade([value("quoted", name="price"), euros])
        self.assertEqual("assumed", result["weakest"])
        self.assertEqual("indicative", result["grade"])

    def test_projected_values_grade_separately_from_estimates(self):
        result = decision_grade([value("measured"), value("projected")])
        self.assertEqual("projected", result["grade"])

    def test_proxies_are_reported_in_the_note(self):
        result = decision_grade([value("measured", proxy_for="cost of the shared host")])
        self.assertEqual(1, len(result["proxies"]))
        self.assertIn("proxy", result["note"])

    def test_profile_counts_by_basis_in_canonical_order(self):
        result = profile([value("assumed"), value("measured"), value("measured")])
        self.assertEqual(["measured", "assumed"], list(result["by_basis"]))
        self.assertEqual(2, result["by_basis"]["measured"])


if __name__ == "__main__":
    unittest.main()