tests/test_regime_detection.py

import sys
import os
import pytest
import numpy as np
import pandas as pd

_this_dir = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, _this_dir)

from regime_detection import detect_volatility_regime, dynamic_risk_aversion
from config import DEFAULT_CONFIG

def test_detect_volatility_regime_sorting():
    rng = np.random.default_rng(42)
    
    # Generate 3 distinct regimes to ensure sorting logic works
    # Low vol (bull), Med vol (normal), High vol (crash)
    rets_low = rng.normal(0.001, 0.005, 100)
    rets_med = rng.normal(0.000, 0.015, 100)
    rets_high = rng.normal(-0.002, 0.040, 100)
    
    # Combine into a single series
    all_rets = np.concatenate([rets_low, rets_med, rets_high])
    series = pd.Series(all_rets)
    
    res = detect_volatility_regime(series, cfg=DEFAULT_CONFIG, silent=True)
    
    # Verify the HMM detected the high vol regime at the end
    assert bool(res["is_high_vol"]) is True
    assert res["current_regime"] == "Crash / High Volatility"
    assert res["severity_score"] > 1.0
    
    # Verify the state sorting worked (variances should be strictly increasing)
    regime_vols = res["details"]["regime_vols"]
    assert regime_vols[0] < regime_vols[1] < regime_vols[2]

def test_dynamic_risk_aversion_vix_crisis():
    """Base inputs (Aggressive profile < 6)"""
    base_input = 4
    base_factor = 2.0
    
    # Crisis VIX
    vix = 40.0
    
    adj_input, adj_factor = dynamic_risk_aversion(vix, base_input, base_factor, silent=True)
    
    # Should clamp aggressive risk profile to conservative
    assert adj_input == 7
    assert adj_factor >= 7.5

def test_dynamic_risk_aversion_vix_complacent():
    """Aggressive inputs"""
    base_input = 8
    base_factor = 2.0
    
    # Complacent VIX
    vix = 10.0
    
    adj_input, adj_factor = dynamic_risk_aversion(vix, base_input, base_factor, silent=True)
    
    assert adj_input == base_input
    assert adj_factor < base_factor

def test_detect_volatility_regime_zeros_boundary():
    """HMM should gracefully handle a completely flat/zero return series without crashing."""
    series = pd.Series(np.zeros(200))
    res = detect_volatility_regime(series, cfg=DEFAULT_CONFIG, silent=True)
    
    # Should fallback to baseline or calm regime
    assert res["severity_score"] == 1.0
    assert not res["is_high_vol"]