a simple fake clock for golang
Replace uses of the time
package with the clockwork.Clock
interface instead.
For example, instead of using time.Sleep
directly:
func myFunc() {
time.Sleep(3 * time.Second)
doSomething()
}
inject a clock and use its Sleep
method instead:
func myFunc(clock clockwork.Clock) {
clock.Sleep(3 * time.Second)
doSomething()
}
Now you can easily test myFunc
with a FakeClock
:
func TestMyFunc(t *testing.T) {
c := clockwork.NewFakeClock()
// Start our sleepy function
var wg sync.WaitGroup
wg.Add(1)
go func() {
myFunc(c)
wg.Done()
}()
// Ensure we wait until myFunc is sleeping
c.BlockUntil(1)
assertState()
// Advance the FakeClock forward in time
c.Advance(3 * time.Second)
// Wait until the function completes
wg.Wait()
assertState()
}
and in production builds, simply inject the real clock instead:
myFunc(clockwork.NewRealClock())
See example_test.go for a full example.
clockwork is inspired by @wickman's threaded fake clock, and the Golang playground