go-clock

A small package that offers testable time functions.

Why?

It is hard to properly test the code that performs time operations relative to the current time or that depends on the time flow, e.g. with time.Now() or time.After(d) calls.

go-clock provides a package-level Clock object that can easily be swapped for a configurable mock in your tests. The package also offers some commonly-used functions from the time package that use the Clock.

Installation

go get github.com/michalkurzeja/go-clock

Usage

In your code, simply use the go-clock functions for time retrieval instead of the standard time package:

import "github.com/michalkurzeja/go-clock"

now := clock.Now() // Instead of `time.Now()`
since := clock.Since(now) // Instead of `time.Since()`
c := clock.After(time.Second) // Instead of `time.After(time.Second)`

In your tests, you can mock the clock to get predictable time output:

fakeNow := time.Date(...)

mock := clock.Mock(fakeNow) // `clock.Now()` will always return `fakeNow` time.
defer clock.Restore()

mock.Add(time.Second) // Advances the fake clock's time by a second.

go-clock uses the clock implementation from the benbjohnson/clock package. For more details on the usage of the clock, please see it's docs.