test(weight-evolver): 순수 함수 + base update rule 단위 테스트

lotto/tests/test_weight_evolver.py

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+# lotto/tests/test_weight_evolver.py
+import json
+import math
+import pytest
+
+from app import weight_evolver as we
+
+
+def test_clamp_and_normalize_min_floor():
+    """모든 값이 0.05 이상이 되도록 보장 + 합=1.0."""
+    W = we.clamp_and_normalize([0.01, 0.6, 0.2, 0.1, 0.09])
+    assert all(w >= 0.05 - 1e-9 for w in W)
+    assert abs(sum(W) - 1.0) < 1e-9
+
+
+def test_clamp_and_normalize_negative_becomes_floor():
+    W = we.clamp_and_normalize([-0.1, 0.5, 0.3, 0.2, 0.1])
+    assert W[0] >= 0.05 - 1e-9
+    assert abs(sum(W) - 1.0) < 1e-9
+
+
+def test_perturbation_changes_around_base():
+    """σ=0.05 정규분포 perturbation 후 정규화 — 각 값이 합리적 범위 안."""
+    base = [0.2, 0.2, 0.2, 0.2, 0.2]
+    W = we.perturb_weights(base, sigma=0.05, seed=42)
+    assert abs(sum(W) - 1.0) < 1e-9
+    assert all(w >= 0.05 - 1e-9 for w in W)
+
+
+def test_dirichlet_random_distribution():
+    """Dirichlet α=2 — 5종 비음수 합=1."""
+    W = we.dirichlet_weights(alpha=2.0, seed=42)
+    assert abs(sum(W) - 1.0) < 1e-9
+    assert all(0.05 - 1e-9 <= w <= 1.0 for w in W)
+
+
+def test_generate_weekly_candidates_count():
+    """6개 후보 생성 — 4 perturb + 2 dirichlet."""
+    base = [0.2, 0.2, 0.2, 0.2, 0.2]
+    trials = we.generate_weekly_candidates(base, seed=42)
+    assert len(trials) == 6
+    sources = [t["source"] for t in trials]
+    assert sources.count("perturb") == 4
+    assert sources.count("dirichlet") == 2
+    days = sorted(t["day_of_week"] for t in trials)
+    assert days == [0, 1, 2, 3, 4, 5]
+
+
+def test_calc_pick_score_six_match():
+    """6개 모두 일치 → 1등 → base=1.0 + bonus 1.0 = 2.0."""
+    score = we.calc_pick_score([1, 2, 3, 4, 5, 6], [1, 2, 3, 4, 5, 6])
+    assert score == pytest.approx(2.0)
+
+
+def test_calc_pick_score_four_match():
+    """4개 일치 → 4등 → base=4/6 + bonus 0.3."""
+    score = we.calc_pick_score([1, 2, 3, 4, 7, 8], [1, 2, 3, 4, 5, 6])
+    assert score == pytest.approx(4/6 + 0.3)
+
+
+def test_calc_pick_score_three_match():
+    """3개 일치 → 5등 → base=3/6 + bonus 0.1."""
+    score = we.calc_pick_score([1, 2, 3, 7, 8, 9], [1, 2, 3, 4, 5, 6])
+    assert score == pytest.approx(3/6 + 0.1)
+
+
+def test_calc_pick_score_two_match_no_bonus():
+    """2개 일치 → 미당첨 → base=2/6 + bonus 0."""
+    score = we.calc_pick_score([1, 2, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6])
+    assert score == pytest.approx(2/6)
+
+
+def test_decide_base_update_winner_4plus_replaces():
+    """winner_max_correct ≥ 4 → 교체."""
+    current = [0.2, 0.2, 0.2, 0.2, 0.2]
+    winner_W = [0.1, 0.3, 0.2, 0.3, 0.1]
+    new_base, reason = we.decide_base_update(
+        winner_max_correct=4,
+        winner_W=winner_W,
+        current_base=current,
+    )
+    assert new_base == winner_W
+    assert reason == "winner_4plus"
+
+
+def test_decide_base_update_winner_3_ema_blend():
+    """winner_max_correct = 3 → 0.3*winner + 0.7*current."""
+    current = [0.2, 0.2, 0.2, 0.2, 0.2]
+    winner_W = [0.1, 0.3, 0.2, 0.3, 0.1]
+    new_base, reason = we.decide_base_update(
+        winner_max_correct=3,
+        winner_W=winner_W,
+        current_base=current,
+    )
+    expected = [0.3 * w + 0.7 * c for w, c in zip(winner_W, current)]
+    assert all(abs(a - b) < 1e-9 for a, b in zip(new_base, expected))
+    assert reason == "ema_blend"
+
+
+def test_decide_base_update_winner_lt3_unchanged():
+    """winner_max_correct ≤ 2 → 직전 base 유지."""
+    current = [0.2, 0.2, 0.2, 0.2, 0.2]
+    winner_W = [0.1, 0.3, 0.2, 0.3, 0.1]
+    new_base, reason = we.decide_base_update(
+        winner_max_correct=2,
+        winner_W=winner_W,
+        current_base=current,
+    )
+    assert new_base == current
+    assert reason == "unchanged"
+
+
+def test_decide_base_update_cold_start_returns_default():
+    """current_base=None (첫 회) → 균등 default 반환."""
+    winner_W = [0.1, 0.3, 0.2, 0.3, 0.1]
+    new_base, reason = we.decide_base_update(
+        winner_max_correct=4,
+        winner_W=winner_W,
+        current_base=None,
+    )
+    assert new_base == winner_W
+    assert reason == "winner_4plus"