import os


def build_conn_string() -> str:
    return (
        f"postgresql://{os.getenv('POSTGRES_USER')}:{os.getenv('POSTGRES_PASSWORD')}@"
        f"{os.getenv('POSTGRES_HOST')}:{os.getenv('POSTGRES_PORT')}/"
        f"{os.getenv('POSTGRES_SETTINGS_DB')}"
    )


def test_connection_string(monkeypatch):
    monkeypatch.setenv("POSTGRES_USER", "user")
    monkeypatch.setenv("POSTGRES_PASSWORD", "pass")
    monkeypatch.setenv("POSTGRES_HOST", "localhost")
    monkeypatch.setenv("POSTGRES_PORT", "5432")
    monkeypatch.setenv("POSTGRES_SETTINGS_DB", "db")

    assert build_conn_string() == "postgresql://user:pass@localhost:5432/db"