k3s/vendor/github.com/jonboulle/clockwork/README.md

clockwork

a simple fake clock for golang

Usage

Replace uses of the time package with the clockwork.Clock interface instead.

For example, instead of using time.Sleep directly:

func my_func() {
	time.Sleep(3 * time.Second)
	do_something()
}

inject a clock and use its Sleep method instead:

func my_func(clock clockwork.Clock) {
	clock.Sleep(3 * time.Second)
	do_something()
}

Now you can easily test my_func with a FakeClock:

func TestMyFunc(t *testing.T) {
	c := clockwork.NewFakeClock()

	// Start our sleepy function
	my_func(c)

	// Ensure we wait until my_func is sleeping
	c.BlockUntil(1)

	assert_state()

	// Advance the FakeClock forward in time
	c.Advance(3)

	assert_state()
}

and in production builds, simply inject the real clock instead:

my_func(clockwork.NewRealClock())

See example_test.go for a full example.

Credits

Inspired by @wickman's threaded fake clock, and the [Golang playground](http://blog.golang.org/playground#Faking time)