fog/test/metrics/levenshtein_test.py

# =============================================================================
# Fog Levenshtein Distance Unit Tests
# =============================================================================
import math
from pytest import approx
from fog.metrics import levenshtein_distance, limited_levenshtein_distance

BASIC_TESTS = [
    # (('b', 'o', 'o', 'k'), ('b', 'a', 'c', 'k'), 2),
    # (('the', 'cat', 'eats', 'mouse'), ('the', 'mouse', 'likes', 'mouse'), 2),
    ('book', 'back', 2),
    ('bbbbookkkk', 'bbbbackkkk', 2),
    ('hello', 'helo', 1),
    ('good sir', 'baal', 8),
    ('say', 'shiver', 5),
    ('feature', 'get-project-features', 13),
    ('example', 'samples', 3),
    ('sturgeon', 'urgently', 6),
    ('levenshtein', 'frankenstein', 6),
    ('distance', 'difference', 5),
    ('a', 'b', 1),
    ('ab', 'ac', 1),
    ('ac', 'bc', 1),
    ('abc', 'axc', 1),
    ('xabxcdxxefxgx', '1ab2cd34ef5g6', 6),
    ('a', '', 1),
    ('ab', 'a', 1),
    ('ab', 'b', 1),
    ('abc', 'ac', 1),
    ('xabxcdxxefxgx', 'abcdefg', 6),
    ('', 'a', 1),
    ('a', 'ab', 1),
    ('b', 'ab', 1),
    ('ac', 'abc', 1),
    ('abcdefg', 'xabxcdxxefxgx', 6),
    ('', '', 0),
    ('a', 'a', 0),
    ('abc', 'abc', 0),
    ('', '', 0),
    ('a', '', 1),
    ('', 'a', 1),
    ('abc', '', 3),
    ('', 'abc', 3),
    ('因為我是中國人所以我會說中文', '因為我是英國人所以我會說英文', 2),
    # (list('因為我是中國人所以我會說中文'), list('因為我是英國人所以我會說英文'), 2)
]


class TestLevenshteinSimilarity(object):
    def test_basics(self):
        for A, B, distance in BASIC_TESTS:
            assert levenshtein_distance(A, B) == distance, '%s // %s => %i' % (A, B, distance)

    def test_limited(self):
        for A, B, distance in BASIC_TESTS:
            assert limited_levenshtein_distance(2, A, B) == (distance if distance <= 2 else 3)