How to Mock Redis EXPIRE, TTL, and PERSIST in Python

import time

class MockRedis:
    def __init__(self):
        self._store = {}
        self._expiry = {}

    def set(self, key, value):
        self._store[key] = value
        self._expiry.pop(key, None)
        return True

    def expire(self, key, ttl_seconds):
        if key not in self._store:
            return False
        self._expiry[key] = time.time() + ttl_seconds
        return True

    def persist(self, key):
        if key not in self._store:
            return False
        if key in self._expiry:
            del self._expiry[key]
            return True
        return False

    def ttl(self, key):
        if key not in self._store:
            return -2
        if key not in self._expiry:
            return -1
        remaining = int(self._expiry[key] - time.time())
        return max(0, remaining)

    def get(self, key):
        if key not in self._store:
            return None
        expire_at = self._expiry.get(key)
        if expire_at is not None and time.time() > expire_at:
            del self._store[key]
            del self._expiry[key]
            return None
        return self._store[key]


if __name__ == "__main__":
    r = MockRedis()
    r.set("session", "abc123")
    print("TTL after set:", r.ttl("session"))
    print("Expire result:", r.expire("session", 5))
    print("TTL after expire:", r.ttl("session"))
    print("Persist result:", r.persist("session"))
    print("TTL after persist:", r.ttl("session"))
    print("GET value:", r.get("session"))