何时执行此LINQ查询?

public class TestClass
{
    public TestClass(int id, string name)
    {
        Name = name;
        Id = id;
    }
    public string Name
    { get; private set; }

    public int Id
    { get; private set; }

    public string Tag
    { get; set; }

    public DateTime Time
    { get; set; }
}

 private static void Main(string[] args)
    {
        List<TestClass> list = new List<TestClass>();

        for (int i = 0; i < 5; i++ )
        {
            TestClass t = new TestClass(i, Guid.NewGuid().ToString());
            t.Tag = i%2 == 0?"Hello":"World";
            list.Add(t);
        }

        var query = list
            .GroupBy(l=>l.Tag);

        Func<IEnumerable<IGrouping<string, TestClass>>, int[]> func = GetIds<string,TestClass>;

        func.BeginInvoke(query, null, null);

        Console.Read();
    }

    private static int[] GetIds<T, U>(IEnumerable<IGrouping<T, U>> query)
    {
        List<int> ints = new List<int>();

        foreach(var y in query)
            ints.Add(y.Count());

        return ints.ToArray();
    }
}

我知道LINQ在集合被迭代之前不会执行,但我只想确保即使查询被异步传递给另一个方法,它仍然保持为true。