public void ShouldHandleGroupBy()
{
var lines = _query.SelectMany(o => o.Lines).ToList().AsQueryable();
var group1 = lines.GroupBy(l => l.OrderId, l => l.Id, (k, lid) => lid.Count()).ToList();
var dynGroup1 = lines.GroupBy("l => l.OrderId", "l => l.Id", "(k, lid) => lid.Count()").Cast <int>().ToList();
var group2 = lines.GroupBy(l => l.OrderId, (k, l) => l.Count()).ToList();
var dynGroup2 = lines.GroupBy("l => l.OrderId", "(k, l) => l.Count()").Cast <int>().ToList();
var group3 = lines.GroupBy(l => l.OrderId).ToList();
var dynGroup3 = lines.GroupBy("l => l.OrderId").Cast <IGrouping <int, OrderLine> >().ToList();
Assert.Equal(group1, dynGroup1);
Assert.Equal(group2, dynGroup2);
Assert.Equal(group3, dynGroup3);
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(null, ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(_query, ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(null, "", ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(_query, "", ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(_query, "Id", ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(null, "", "", ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(_query, "", "", ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(_query, "Id", "", ""));
Assert.Throws <ArgumentNullException>(() => Dyn.GroupBy(_query, "Id", "Id", ""));
}
