from composer_ans.analysis import analyze_composition


def test_entropy_distinguishes_constant_and_varied_sequences() -> None:
    constant = analyze_composition((1, 1, 1, 1))
    varied = analyze_composition((1, 2, 3, 4))

    assert constant.unigram_entropy_bits == 0.0
    assert varied.unigram_entropy_bits > constant.unigram_entropy_bits


def test_analysis_reports_predictability_for_repeating_pattern() -> None:
    repeating = analyze_composition((1, 2, 1, 2, 1, 2, 1, 2))

    assert repeating.conditional_entropy_bits < repeating.unigram_entropy_bits
    assert 0.0 <= repeating.predictability <= 1.0