use chrono::{DateTime, Utc};use parking_lot::Mutex;use std::time::{Duration, Instant}; pub trait Clock {    fn utc_now(&self) -> DateTime<Utc>;    fn now(&self) -> Instant;} pub struct TestClock(Mutex<TestClockState>); struct TestClockState {    now: Instant,    utc_now: DateTime<Utc>,} impl TestClock {    pub fn new() -> Self {        const START_TIME: &str = "2025-07-01T23:59:58-00:00";        let utc_now = DateTime::parse_from_rfc3339(START_TIME).unwrap().to_utc();        Self(Mutex::new(TestClockState {            now: Instant::now(),            utc_now,        }))    }     pub fn set_utc_now(&self, now: DateTime<Utc>) {        let mut state = self.0.lock();        state.utc_now = now;    }     pub fn advance(&self, duration: Duration) {        let mut state = self.0.lock();        state.now += duration;        state.utc_now += duration;    }} impl Clock for TestClock {    fn utc_now(&self) -> DateTime<Utc> {        self.0.lock().utc_now    }     fn now(&self) -> Instant {        self.0.lock().now    }}