public void A_Intersperse_must_inject_element_between_existing_elements()
{
var probe =
Source.From(new[] { 1, 2, 3 })
.Select(x => x.ToString())
.Intersperse(",")
.RunWith(this.SinkProbe<string>(), Materializer);
probe.ExpectSubscription();
probe.ToStrict(TimeSpan.FromSeconds(1)).Aggregate((s, s1) => s + s1).Should().Be("1,2,3");
}