/nltk/test/unit/lm/test_preprocessing.py

# Natural Language Toolkit: Language Model Unit Tests
#
# Copyright (C) 2001-2026 NLTK Project
# Author: Ilia Kurenkov <ilia.kurenkov@gmail.com>
# URL: <https://www.nltk.org/>
# For license information, see LICENSE.TXT
import unittest

from nltk.lm.preprocessing import padded_everygram_pipeline


class TestPreprocessing(unittest.TestCase):
    def test_padded_everygram_pipeline(self):
        expected_train = [
            [
                ("<s>",),
                ("<s>", "a"),
                ("a",),
                ("a", "b"),
                ("b",),
                ("b", "c"),
                ("c",),
                ("c", "</s>"),
                ("</s>",),
            ]
        ]
        expected_vocab = ["<s>", "a", "b", "c", "</s>"]
        train_data, vocab_data = padded_everygram_pipeline(2, [["a", "b", "c"]])
        self.assertEqual([list(sent) for sent in train_data], expected_train)
        self.assertEqual(list(vocab_data), expected_vocab)