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| """Tests for shared analysis utilities (gini_coefficient, etc.).""" | |
| from __future__ import annotations | |
| import pytest | |
| from obliteratus.analysis.utils import gini_coefficient | |
| class TestGiniCoefficient: | |
| """Tests for the Gini coefficient computation.""" | |
| def test_empty_list(self): | |
| assert gini_coefficient([]) == 0.0 | |
| def test_single_value(self): | |
| assert gini_coefficient([42.0]) == 0.0 | |
| def test_uniform_distribution(self): | |
| """All-equal values → Gini = 0.""" | |
| assert gini_coefficient([1.0, 1.0, 1.0, 1.0]) == pytest.approx(0.0, abs=1e-10) | |
| def test_maximally_concentrated(self): | |
| """One value, rest zero → Gini ≈ 1.""" | |
| result = gini_coefficient([100.0, 0.0, 0.0, 0.0]) | |
| assert result > 0.7 # For n=4, max Gini = (n-1)/n = 0.75 | |
| def test_all_zeros(self): | |
| assert gini_coefficient([0.0, 0.0, 0.0]) == 0.0 | |
| def test_two_equal_values(self): | |
| assert gini_coefficient([5.0, 5.0]) == pytest.approx(0.0, abs=1e-10) | |
| def test_two_unequal_values(self): | |
| """[0, 10] → Gini = 0.5 for n=2.""" | |
| result = gini_coefficient([0.0, 10.0]) | |
| assert result == pytest.approx(0.5, abs=0.01) | |
| def test_moderate_inequality(self): | |
| """Moderate spread → Gini between 0 and 1.""" | |
| result = gini_coefficient([1.0, 2.0, 3.0, 4.0, 5.0]) | |
| assert 0.1 < result < 0.5 | |
| def test_result_in_valid_range(self): | |
| """Gini is always in [0, 1].""" | |
| for vals in [[1, 2, 3], [0, 0, 100], [5, 5, 5], [1], [0.1, 0.9]]: | |
| result = gini_coefficient(vals) | |
| assert 0.0 <= result <= 1.0, f"Gini({vals}) = {result} out of range" | |
| def test_large_uniform(self): | |
| """Large uniform distribution → Gini ≈ 0.""" | |
| vals = [1.0] * 1000 | |
| assert gini_coefficient(vals) == pytest.approx(0.0, abs=1e-10) | |
| def test_large_concentrated(self): | |
| """Large distribution with one outlier → high Gini.""" | |
| vals = [0.0] * 999 + [1000.0] | |
| result = gini_coefficient(vals) | |
| assert result > 0.99 | |
| def test_order_invariant(self): | |
| """Gini should not depend on input order.""" | |
| a = gini_coefficient([1.0, 3.0, 5.0, 7.0]) | |
| b = gini_coefficient([7.0, 1.0, 5.0, 3.0]) | |
| assert a == pytest.approx(b) | |