public void SouldNotAllowSelectorNullGroupBy()
{
var builder = new StreamBuilder();
IKStream <string, string> stream = builder.Stream <string, string>("topic");
Func <string, string, string> selector1 = null;
IKeyValueMapper <string, string, string> selector2 = null;
Assert.Throws <ArgumentNullException>(() => stream.GroupBy(selector1));
Assert.Throws <ArgumentNullException>(() => stream.GroupBy(selector2));
Assert.Throws <ArgumentNullException>(() => stream.GroupBy <string, StringSerDes>(selector1));
Assert.Throws <ArgumentNullException>(() => stream.GroupBy <string, StringSerDes>(selector2));
}
