import pytest
import yaml

@pytest.fixture(scope="session")
def env_config():
    # A fixture to read the config file once per session.
    # In a real-world scenario, you might add logic here to select
    # different config files (e.g., dev, prod) based on a command-line argument.
    with open('config/dev_env.yaml', 'r') as file:
        return yaml.safe_load(file)

@pytest.fixture(scope="session")
def base_url(env_config):
    """
    Provides the base URL for the application under test.
    """
    url = env_config.get('base_url')
    if not url:
        raise Exception("'base_url' not found in config file.")
    return url