"""The tests for the Demo component."""
import json
from unittest.mock import patch

import pytest

from homeassistant.components.demo import DOMAIN
from homeassistant.core import HomeAssistant
from homeassistant.helpers.json import JSONEncoder
from homeassistant.setup import async_setup_component


@pytest.fixture
def mock_history(hass):
    """Mock history component loaded."""
    hass.config.components.add("history")


@pytest.fixture(autouse=True)
def mock_device_tracker_update_config():
    """Prevent device tracker from creating known devices file."""
    with patch("homeassistant.components.device_tracker.legacy.update_config"):
        yield


async def test_setting_up_demo(mock_history, hass: HomeAssistant) -> None:
    """Test if we can set up the demo and dump it to JSON."""
    assert await async_setup_component(hass, DOMAIN, {DOMAIN: {}})
    await hass.async_block_till_done()
    await hass.async_start()

    # This is done to make sure entity components don't accidentally store
    # non-JSON-serializable data in the state machine.
    try:
        json.dumps(hass.states.async_all(), cls=JSONEncoder)
    except Exception:  # pylint: disable=broad-except
        pytest.fail(
            "Unable to convert all demo entities to JSON. Wrong data in state machine!"
        )