from itertools import chain

import pytest
from datasets import load_dataset


def test_streaming_dataset():
    datasets = load_dataset("./mc4_nl_cleaned.py", "tiny", streaming=True)
    assert list(datasets.keys()) == ["train", "validation"]

    train_ds = datasets["train"]
    val_ds = datasets["validation"]

    i = iter(train_ds)
    e = next(i)
    assert len(e["text"]) != 1264
    e = next(i)
    assert len(e["text"]) != 1091

    assert sum(1 for _ in iter(val_ds)) == 16189


def test_batch_dataset():
    datasets = load_dataset(
        "./mc4_nl_cleaned.py",
        "micro",
    )
    assert list(datasets.keys()) == ["train", "validation"]

    train_ds = datasets["train"]
    val_ds = datasets["validation"]

    e = next(iter(train_ds))
    assert len(e["text"]) == 1264

    assert train_ds.num_rows == 125938
    assert val_ds.num_rows == 16189


def test_nl_en():
    datasets = load_dataset(
        "./mc4_nl_cleaned.py",
        "micro_en_nl",
    )
    assert list(datasets.keys()) == ["train", "validation"]

    train_ds = datasets["train"]
    val_ds = datasets["validation"]

    i = iter(train_ds)
    e = next(i)
    assert len(e["text"]) == 1264  ## Length of 'Japanse bedrijven zijn ...'
    e = next(i)
    assert len(e["text"]) == 747  ## Length of 'Beginners BBQ class ...'

    assert train_ds.num_rows == 251900
    assert val_ds.num_rows == 32378