A simple fake clock for Go.
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) {
ctx := context.Background()
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 waiting on the clock.
// Use a context to avoid blocking forever if something
// goes wrong.
ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel()
c.BlockUntilContext(ctx, 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
Apache License, Version 2.0. Please see License File for more information.