import numpy as np
from tests.node_tests._shared import make_field


def test_statistics():
    from backend.nodes.statistics import Statistics
    node = Statistics()

    data = np.array([[1, 2], [3, 4]], dtype=np.float64)
    field = make_field(data=data)

    table, = node.process(field)
    stats = {row["quantity"]: row["value"] for row in table}

    assert stats["min"] == 1.0
    assert stats["max"] == 4.0
    assert stats["mean"] == 2.5
    assert stats["median"] == 2.5
    assert stats["range"] == 3.0
    expected_rms = np.sqrt(np.mean((data - 2.5) ** 2))
    assert abs(stats["RMS"] - expected_rms) < 1e-10

    const_field = make_field(data=np.ones((4, 4)) * 5.0)
    table_const, = node.process(const_field)
    const_stats = {row["quantity"]: row["value"] for row in table_const}
    assert const_stats["RMS"] == 0.0
    assert const_stats["skewness"] == 0.0
    assert const_stats["kurtosis"] == 0.0