EnumerableExtensions.cs

public static class EnumerableExtensions
{
    public static IEnumerable<IEnumerable<TSource>> SplitWithRest<TSource>(this IEnumerable<TSource> source, params Func<TSource, bool>[] predicates)
    {
        var taken = new List<TSource>();

        for (int i = 0, l = predicates.Length; i < l; i++)
        {
            var take = source.Where(predicates[i]);
            taken.AddRange(take);
            yield return take;
        }

        yield return source.Where(c => !taken.Contains(c));
    }
}

[TestClass()]
public class EnumerableExtensionsTests
{
    [TestMethod()]
    public void SplitWithRestTest()
    {
        var set = new int[] { 0, 1, 2 };

        var sets = set.SplitWithRest(
            c => c == 0,
            c => c == 1
        ).ToArray(); 
            
        Assert.AreEqual(3, sets.Length);

        var subset0 = sets[0].ToArray();
        Assert.AreEqual(1, subset0.Length);
        Assert.AreEqual(0, subset0[0]);

        var subset1 = sets[1].ToArray();
        Assert.AreEqual(1, subset1.Length);
        Assert.AreEqual(1, subset1[0]);

        var subset2 = sets[2].ToArray();
        Assert.AreEqual(1, subset2.Length);
        Assert.AreEqual(2, subset2[0]);
    }

    [TestMethod()]
    public void SplitWithRestOverlapTest()
    {
        var set = new int[] { 0, 1, 2, 3, 4, 5 };

        var sets = set.SplitWithRest(
            c => c == 0,
            c => c == 1,
            c => c == 2 || c == 3,
            c => c >= 3 && c < 5
        ).ToArray();

        Assert.AreEqual(5, sets.Length);

        var subset0 = sets[0].ToArray();
        Assert.AreEqual(1, subset0.Length);
        Assert.AreEqual(0, subset0[0]);

        var subset1 = sets[1].ToArray();
        Assert.AreEqual(1, subset1.Length);
        Assert.AreEqual(1, subset1[0]);

        var subset2 = sets[2].ToArray();
        Assert.AreEqual(2, subset2.Length);
        Assert.AreEqual(2, subset2[0]);
        Assert.AreEqual(3, subset2[1]);

        var subset3 = sets[3].ToArray();
        Assert.AreEqual(2, subset3.Length);
        Assert.AreEqual(3, subset3[0]);
        Assert.AreEqual(4, subset3[1]);

        var subset4 = sets[4].ToArray();
        Assert.AreEqual(1, subset4.Length);
        Assert.AreEqual(5, subset4[0]);
    }

    [TestMethod()]
    public void SplitWithRestNoRestTest()
    {
        var set = new int[] { 0, 1, 2, 3, 4, 5 };

        var sets = set.SplitWithRest(
            c => c <= 2,
            c => c > 2
        ).ToArray();

        Assert.AreEqual(3, sets.Length);

        var subset0 = sets[0].ToArray();
        Assert.AreEqual(3, subset0.Length);
        Assert.AreEqual(0, subset0[0]);
        Assert.AreEqual(1, subset0[1]);
        Assert.AreEqual(2, subset0[2]);

        var subset1 = sets[1].ToArray();
        Assert.AreEqual(3, subset1.Length);
        Assert.AreEqual(3, subset1[0]);
        Assert.AreEqual(4, subset1[1]);
        Assert.AreEqual(5, subset1[2]);

        var subset3 = sets[2].ToArray();
        Assert.AreEqual(0, subset3.Length);
    }
}