tests/unit/test_config.py

"""Unit tests for app.config (SETUP-03).

These tests exercise `app.config.load_settings()` directly, using only
monkeypatched (fake) environment values -- never the project's real `.env`
or real secrets.
"""

from __future__ import annotations

import pytest

from app.config import ConfigError, load_settings

VALID_ENV = {
    "DB_HOST": "test-db-host.invalid",
    "DB_PORT": "3306",
    "DB_NAME": "test_db",
    "DB_USER": "test_user",
    "DB_PASSWORD": "test-password-not-real",
    "DATABASE_URL": (
        "mysql+pymysql://test_user:test-password-not-real"
        "@test-db-host.invalid:3306/test_db"
    ),
    "APP_PORT": "8000",
    "ALLOWED_ORIGINS": "https://example.test,https://other.example.test",
    "FRAUD_ALERT_THRESHOLD": "0.5",
    "MODEL_PATH": "training/artifacts/model_v1.pkl",
    "SEED_OFFICER_EMAIL": "officer@example.test",
    "SEED_OFFICER_PASSWORD": "fake-seed-password-not-real",
    "SESSION_EXPIRE_MINUTES": "1440",
    "KAGGLE_USERNAME": "fake-kaggle-user",
    "KAGGLE_KEY": "fake-kaggle-key-not-real",
}


@pytest.fixture
def valid_env(monkeypatch: pytest.MonkeyPatch) -> None:
    """Set a complete, fully-fake, valid environment for each test."""
    for key, value in VALID_ENV.items():
        monkeypatch.setenv(key, value)


def test_complete_env_yields_typed_settings(valid_env: None) -> None:
    settings = load_settings()

    assert settings.DB_HOST == VALID_ENV["DB_HOST"]
    assert settings.DB_PORT == 3306
    assert isinstance(settings.DB_PORT, int)
    assert settings.DB_NAME == VALID_ENV["DB_NAME"]
    assert settings.DB_USER == VALID_ENV["DB_USER"]
    assert settings.DB_PASSWORD == VALID_ENV["DB_PASSWORD"]
    assert settings.DATABASE_URL == VALID_ENV["DATABASE_URL"]
    assert settings.APP_PORT == 8000
    assert isinstance(settings.APP_PORT, int)
    assert settings.ALLOWED_ORIGINS == [
        "https://example.test",
        "https://other.example.test",
    ]
    assert settings.FRAUD_ALERT_THRESHOLD == pytest.approx(0.5)
    assert isinstance(settings.FRAUD_ALERT_THRESHOLD, float)
    assert settings.MODEL_PATH == VALID_ENV["MODEL_PATH"]
    assert settings.SEED_OFFICER_EMAIL == VALID_ENV["SEED_OFFICER_EMAIL"]
    assert settings.SEED_OFFICER_PASSWORD == VALID_ENV["SEED_OFFICER_PASSWORD"]
    assert settings.SESSION_EXPIRE_MINUTES == 1440
    assert isinstance(settings.SESSION_EXPIRE_MINUTES, int)
    assert settings.KAGGLE_USERNAME == VALID_ENV["KAGGLE_USERNAME"]
    assert settings.KAGGLE_KEY == VALID_ENV["KAGGLE_KEY"]


@pytest.mark.parametrize(
    "missing_var",
    [
        "DB_HOST",
        "DB_NAME",
        "DB_USER",
        "DB_PASSWORD",
        "DATABASE_URL",
        "ALLOWED_ORIGINS",
        "FRAUD_ALERT_THRESHOLD",
        "MODEL_PATH",
        "DB_PORT",
        "SEED_OFFICER_EMAIL",
        "SEED_OFFICER_PASSWORD",
    ],
)
def test_missing_required_var_raises_config_error_naming_the_variable(
    valid_env: None, monkeypatch: pytest.MonkeyPatch, missing_var: str
) -> None:
    monkeypatch.delenv(missing_var, raising=False)

    with pytest.raises(ConfigError) as exc_info:
        load_settings()

    message = str(exc_info.value)
    assert missing_var in message
    # Never echo secret-ish values in the error message.
    assert VALID_ENV["DB_PASSWORD"] not in message
    assert VALID_ENV["KAGGLE_KEY"] not in message


def test_out_of_range_fraud_alert_threshold_raises_config_error(
    valid_env: None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.setenv("FRAUD_ALERT_THRESHOLD", "1.5")

    with pytest.raises(ConfigError) as exc_info:
        load_settings()

    assert "FRAUD_ALERT_THRESHOLD" in str(exc_info.value)


def test_non_numeric_fraud_alert_threshold_raises_config_error(
    valid_env: None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.setenv("FRAUD_ALERT_THRESHOLD", "not-a-number")

    with pytest.raises(ConfigError) as exc_info:
        load_settings()

    assert "FRAUD_ALERT_THRESHOLD" in str(exc_info.value)


def test_unparseable_db_port_raises_config_error(
    valid_env: None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.setenv("DB_PORT", "not-an-int")

    with pytest.raises(ConfigError) as exc_info:
        load_settings()

    assert "DB_PORT" in str(exc_info.value)


def test_missing_app_port_falls_back_to_default(
    valid_env: None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.delenv("APP_PORT", raising=False)

    settings = load_settings()

    assert settings.APP_PORT == 8000


def test_unparseable_app_port_raises_config_error(
    valid_env: None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.setenv("APP_PORT", "not-an-int")

    with pytest.raises(ConfigError) as exc_info:
        load_settings()

    assert "APP_PORT" in str(exc_info.value)


def test_missing_session_expire_minutes_falls_back_to_default(
    valid_env: None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.delenv("SESSION_EXPIRE_MINUTES", raising=False)

    settings = load_settings()

    assert settings.SESSION_EXPIRE_MINUTES == 1440