"""Unit tests for the :mod:`networkx.generators.sudoku_graph` module."""

import pytest
import networkx as nx


def test_sudoku_negative():
    """Raise an error when generating a Sudoku graph of order -1."""
    pytest.raises(nx.NetworkXError, nx.sudoku_graph, n=-1)


@pytest.mark.parametrize("n", [0, 1, 2, 3, 4])
def test_sudoku_generator(n):
    """Generate Sudoku graphs of various sizes and verify their properties."""
    G = nx.sudoku_graph(n)
    expected_nodes = n ** 4
    expected_degree = (n - 1) * (3 * n + 1)
    expected_edges = expected_nodes * expected_degree // 2
    assert not G.is_directed()
    assert not G.is_multigraph()
    assert G.number_of_nodes() == expected_nodes
    assert G.number_of_edges() == expected_edges
    assert all(d == expected_degree for _, d in G.degree)

    if n == 2:
        assert sorted(G.neighbors(6)) == [2, 3, 4, 5, 7, 10, 14]
    elif n == 3:
        assert sorted(G.neighbors(42)) == [
            6,
            15,
            24,
            33,
            34,
            35,
            36,
            37,
            38,
            39,
            40,
            41,
            43,
            44,
            51,
            52,
            53,
            60,
            69,
            78,
        ]
    elif n == 4:
        assert sorted(G.neighbors(0)) == [
            1,
            2,
            3,
            4,
            5,
            6,
            7,
            8,
            9,
            10,
            11,
            12,
            13,
            14,
            15,
            16,
            17,
            18,
            19,
            32,
            33,
            34,
            35,
            48,
            49,
            50,
            51,
            64,
            80,
            96,
            112,
            128,
            144,
            160,
            176,
            192,
            208,
            224,
            240,
        ]
