hypothesis_property_test_encode_decode_string_roundtrip.py

1from hypothesis import given
2from hypothesis.strategies import text
3
4def encode(input_string):
5    if not input_string:
6        return []
7    count = 1
8    prev = input_string[0]
9    result = []
10    for char in input_string[1:]:
11        if char == prev:
12            count += 1
13        else:
14            result.append((count, prev))
15            count = 1
16            prev = char
17    result.append((count, prev))
18    return result
19
20def decode(lst):
21    res = ""
22    for count, char in lst:
23        res += char * count
24    return res
25
26@given(text())
27def test_decode_inverts_encode(s):
28    assert decode(encode(s)) == s
29
30if __name__ == "__main__":
31    test_decode_inverts_encode()