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Python Python Testing Be Assertive assertRaises

Not sure where is the mistake

Please check

tests.py
import unittest

from string_fun import get_anagrams

class AnagramTestCase(unittest.TestCase):
    def test_empty_string(self):
        with self.assertRaises(ValueError):
                  self.get_anagrams()
string_fun.py
import itertools


def is_palindrome(yarn):
    """Return whether or not a string is a palindrome.

    A palindrome is a word/phrase that's the same in
    both directions.
    """
    return yarn == yarn[::-1]


def get_anagrams(*yarn):
    """Return a list of anagrams for a string."""
    # If only one letter came in, return it
    if yarn:
        if len(yarn[0]) == 1:
            return list(yarn)
        elif len(yarn[0] == 0):
            raise ValueError("Must provide at least two letters")
    else:
        raise ValueError("Must provide at least two letters")

    # Get all of the words from the dictionary
    words = set([
        w.strip().lower() for w in open('words.txt')
    ])

    output = set()
    for thread in yarn:
        thread = thread.lower()
        # Find all possible anagrams
        for i in range(2, len(thread)):
            fibers = set(
                [''.join(w) for w in itertools.permutations(thread, i)]
            )
            output.update(fibers.intersection(words))

    # Finally, return all of the combinations that are in the dictionary
    return sorted(list(output))

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points

The error is in the exercise of get_anagrams() function. The test is checking if an error is raised when an empty string is passed in, so the test code has to pass the empty string. See below:

class AnagramTestCase(unittest.TestCase):
    def test_empty_string(self):
        with self.assertRaises(ValueError):
            get_anagrams('')  #<-- pass empty string