Crate mock_instant
source ·Expand description
§mock_instant
This crate allows you to test Instant/Duration code, deterministically per thread.
If cross-thread determinism is required, enable the sync
feature:
mock_instant = { version = "0.2", features = ["sync"] }
It provides a replacement std::time::Instant
and std::time::SystemTime
that uses a deterministic thread-local ‘clock’
NOTE: if this is enabled then all tests will use the same singleton MockClock
source
You can swap out the std::time::Instant
with this one by doing something similar to:
#[cfg(test)]
use mock_instant::Instant;
#[cfg(not(test))]
use std::time::Instant;
or for a std::time::SystemTime
#[cfg(test)]
use mock_instant::{SystemTime, SystemTimeError};
#[cfg(not(test))]
use std::time::{SystemTime, SystemTimeError};
§Example
use std::time::Duration;
let now = Instant::now();
MockClock::advance(Duration::from_secs(15));
MockClock::advance(Duration::from_secs(2));
// its been '17' seconds
assert_eq!(now.elapsed(), Duration::from_secs(17));
§Mocking a SystemTime
use std::time::Duration;
let now = SystemTime::now();
MockClock::advance_system_time(Duration::from_secs(15));
MockClock::advance_system_time(Duration::from_secs(2));
// its been '17' seconds
assert_eq!(now.elapsed().unwrap(), Duration::from_secs(17));
Structs§
- A simple deterministic Instant wrapped around a modifiable Duration
- A Mock clock
- A simple deterministic SystemTime wrapped around a modifiable Duration
- An error returned from the duration_since and elapsed methods on SystemTime, used to learn how far in the opposite direction a system time lies.