code for detecting anagrams with tests

anagram.py

from collections import Counter
from unittest.case import TestCase


def is_anagram(word1, word2):
    def extract_counter(word):
        counter = Counter(filter(lambda char: char != ' ', word))
        return counter

    counter1 = extract_counter(word1)
    counter2 = extract_counter(word2)

    return counter1 == counter2


class AnagramTests(TestCase):
    def test_ignoring_empty_char(self):
        self.assertTrue(is_anagram(' ', ''))
        self.assertTrue(is_anagram('a', ' a '))
        self.assertTrue(is_anagram(' a', ' a '))
        self.assertTrue(is_anagram(' a    ', ' a '))

    def test_not_anagrams(self):
        self.assertFalse(is_anagram(' ', 'a'))
        self.assertFalse(is_anagram('a', ' ab'))
        self.assertFalse(is_anagram(' a', ' ca'))
        self.assertFalse(is_anagram('aa', 'ab'))
        self.assertFalse(is_anagram('aa', 'aac'))

    def test_palindromes(self):
        '''
        Palindrome is a very special case of anagram
        where one word is equals to other reversed
        :return:
        '''
        self.assertTrue(is_anagram('a', 'a'))
        self.assertTrue(is_anagram('ba', ' ab '))
        self.assertTrue(is_anagram('Roma me tem amor', 'roma met em amoR'))

    def test_anagrams_with_3_different_chars(self):
        self.assertTrue(is_anagram('abc', 'abc'))
        self.assertTrue(is_anagram('abc', 'acb'))
        self.assertTrue(is_anagram('abc', 'bac'))
        self.assertTrue(is_anagram('abc', 'bca'))
        self.assertTrue(is_anagram('abc', 'cab'))
        self.assertTrue(is_anagram('abc', 'cba'))

    def test_anagrams_with_repeated_chars(self):
        self.assertTrue(is_anagram('aac', 'aac '))
        self.assertTrue(is_anagram('aac', 'aca '))
        self.assertTrue(is_anagram('aac', ' caa '))