public void TestMutabilification()
{
// Make a single block mutable
VList <int> v = new VList <int>(1, 0);
WList <int> w = v.ToWList();
ExpectList(w, 1, 0);
w[1] = 2;
ExpectList(w, 1, 2);
ExpectList(v, 1, 0);
// Make another block, make the front block mutable, then the block-of-2
v.Push(-1);
w = v.ToWList();
w[2] = 3;
ExpectList(w, 1, 0, 3);
Assert.That(w.WithoutLast(1) == v.WithoutLast(1));
w[1] = 2;
ExpectList(w, 1, 2, 3);
Assert.That(w.WithoutLast(1) != v.WithoutLast(1));
// Now for a more complicated case: create a long immutable chain by
// using a nasty access pattern, add a mutable block in front, then
// make some of the immutable blocks mutable. This will cause several
// immutable blocks to be consolidated into one mutable block,
// shortening the chain.
v = new VList <int>(6);
v = v.Add(-1).Tail.Add(5).Add(-1).Tail.Add(4).Add(-1).Tail.Add(3);
v = v.Add(-1).Tail.Add(2).Add(-1).Tail.Add(1).Add(-1).Tail.Add(0);
ExpectList(v, 6, 5, 4, 3, 2, 1, 0);
// At this point, every block in the chain has only one item (it's
// a linked list!) and the capacity of each block is 2.
Assert.AreEqual(7, v.BlockChainLength);
w = v.ToWList();
w.AddRange(new int[] { 1, 2, 3, 4, 5 });
Assert.AreEqual(w.Count, 12);
ExpectList(w, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5);
// Indices: 0 1 2 3 4 5 6 7 8 9 10 11
// Blocks: H| G| F| E| D| C| B | block A (front of chain)
Assert.AreEqual(8, w.BlockChainLength);
Assert.AreEqual(4, w.LocalCount);
w[3] = -3;
ExpectList(w, 6, 5, 4, -3, 2, 1, 0, 1, 2, 3, 4, 5);
// Indices: 0 1 2 3 4 5 6 7 8 9 10 11
// Blocks: H| G| F| block I | block A (front of chain)
Assert.AreEqual(5, w.BlockChainLength);
}