import pytest

from users.utils.dataloader_util import format_for_dataloader


@pytest.mark.parametrize(
    'items, keys, expected',
    [
        pytest.param(
            [],
            [],
            [],
            id='Empty still populates',
        ),
        pytest.param(
            [],
            ['123', '456'],
            [None, None],
            id='Empty items populates',
        ),
        pytest.param(
            [{'user_id': '123'}],
            ['123', '456'],
            [{'user_id': '123'}, None],
            id='Empty items populates',
        ),
        pytest.param(
            [{'user_id': 789}],
            ['123', '456'],
            [None, None],
            id='Disregards irrelevant items',
        ),
        pytest.param(
            [{'user_id': '456'}, {'user_id': '123'}],
            ['123', '456'],
            [{'user_id': '123'}, {'user_id': '456'}],
            id='Orders items based on keys',
        ),
        pytest.param(
            [{'user_id': '123'}, {'user_id': '123', 'something': 'else'}],
            ['123', '456'],
            [{'user_id': '123', 'something': 'else'}, None],
            id='When duplicate key is present in list, uses the latter item',
        ),
        pytest.param(
            [{'user_id': '123'}, {'user_id': '456'}],
            ['123', '456'],
            [{'user_id': '123'}, {'user_id': '456'}],
            id='Returns items matching keys',
        ),
    ],
)
def test_format_for_dataloader(
    items,
    keys,
    expected,
) -> None:
    """Test format_for_dataloader."""
    result = format_for_dataloader(items, keys, 'user_id')
    assert result == expected


def test_format_for_dataloader_exceptions():
    """Test format for dataloader raises exception when lookup key does not exist"""
    with pytest.raises(KeyError):
        format_for_dataloader(
            [{'user_id': '123'}],
            ['123'],
            'lookup_key_does_not_exist',
        )