huffman-py/test_huffman.py

#
#     Sam Hadow - Huffman-py
#     Copyright (C) 2023
#
#     This program is free software: you can redistribute it and/or modify
#     it under the terms of the GNU General Public License as published by
#     the Free Software Foundation, either version 3 of the License, or
#     (at your option) any later version.
#
#     This program is distributed in the hope that it will be useful,
#     but WITHOUT ANY WARRANTY; without even the implied warranty of
#     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#     GNU General Public License for more details.
#
#     You should have received a copy of the GNU General Public License
#     along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

import unittest
from huffman_py.Node import *
from huffman_py.Tree import *
from huffman_py.functions.encode import *
from huffman_py.functions.decode import *
from huffman_py.functions.occurence import *

# Tu run unit tests:
# python -m unittest discover

class TestUtils(unittest.TestCase):
    def test_Tree_id(self):
        a = Node(10, 'a')
        b = Node(8,'b')
        r1 = Node(18,'',left=b,right=a)

        tree1 = Tree(r1)

        # unique identifier check
        id_list = []
        check_id = True
        for elem in tree1.nodes:
            id_list.append(elem.identifier)
        if len(id_list) > len(set(id_list)):
            check_id  = False

        self.assertTrue(check_id)

    def test_Tree_fusion(self):
        # tree merge
        # we must find elements in initial trees + a root
        # identifiers must be unique
        a = Node(10, 'a')
        b = Node(8,'b')
        r1 = Node(18,'',left=b,right=a)
        c = Node(15, 'c')
        d = Node(20,'d')
        r2 = Node(18,'',left=d,right=c)

        tree1 = Tree(r1)
        tree2 = Tree(r2)

        l1 = len(tree1.nodes)
        l2 = len(tree2.nodes)
        tree1 += tree2
        check_fusion = True
        if l1+l2+1 != len(tree1.nodes):
            check_fusion = False

        id_list2 = []
        check_id2 = True
        for elem in tree1.nodes:
            id_list2.append(elem.identifier)
        if len(id_list2) > len(set(id_list2)):
            check_id2  = False

        self.assertTrue(check_fusion)
        self.assertTrue(check_id2)

    def test_Tree_seek(self):
        # seek a node
        a = Node(10, 'a')
        b = Node(8,'b')
        r1 = Node(18,'',left=b,right=a)

        tree1 = Tree(r1)

        self.assertEqual(tree1.seek(a),a)
        self.assertNotEqual(tree1.seek(b),a)

    def test_Tree_delete(self):
        a = Node(10, 'a')
        b = Node(8,'b')
        r1 = Node(18,'',left=b,right=a)
        r2 = Node(18,'',left=None,right=r1)

        tree1 = Tree(r2)

        tree1 -= r1
        self.assertEqual(tree1.seek(a),None)
        self.assertEqual(tree1.seek(b),None)
        self.assertEqual(tree1.seek(r1),None)
        self.assertEqual(tree1.seek(r2),r2)

    def test_occurences(self):
        o1 = calcul_occurence('aaabcc')
        o2 = calcul_occurence('bacaac')
        # Same dictionary in both case
        # 3 for a, 2 for c, 1 for b
        self.assertEqual(o1,o2)
        self.assertEqual(o1['c'],2)
        self.assertEqual(o1['b'],1)
        self.assertEqual(o1['a'],3)


    def test_huffman_encode(self):
        string = 'sheep'
        string2 = 'cow'
        (encodedOutput, root, huffmanEncoding) = huffman_encode(string)
        (encodedOutput2, root2, huffmanEncoding2) = huffman_encode(string2)
        # encoding must be different
        self.assertNotEqual(huffmanEncoding, huffmanEncoding2)
        self.assertNotEqual(encodedOutput, encodedOutput2)
        self.assertNotEqual(Tree(root),Tree(root2))

    def test_decodage_huffman(self):
        string = 'chicken'
        (encodedOutput, root, huffmanEncoding) = huffman_encode(string)
        # We must be able to decode a binary from its tree root/dict
        self.assertEqual(string,huffman_decode(encodedOutput,root))
        self.assertEqual(string,decode_from_dict(encodedOutput,huffmanEncoding))

        # we must be able to detect if tree/dict isn't the correct one to decode a binary
        string2 = 'pig'
        (encodedOutput2, root2, huffmanEncoding2) = huffman_encode(string2)
        with self.assertRaises(ValueError):
            decode_from_dict(encodedOutput2,huffmanEncoding)
        with self.assertRaises(ValueError):
            huffman_decode(encodedOutput2,root)


if __name__ == '__main__':
    unittest.main()