public void ChunkSourceLazily()
{
using IEnumerator <int[]> chunks = new FastInfiniteEnumerator <int>().Chunk(5).GetEnumerator();
chunks.MoveNext();
Assert.Equal(new[] { 0, 0, 0, 0, 0 }, chunks.Current);
Assert.True(chunks.MoveNext());
}
public void IteratorStateShouldNotChangeIfNumberOfElementsIsUnbounded()
{
// With https://github.com/dotnet/corefx/pull/13628, Skip and Take return
// the same type of iterator. For Take, there is a limit, or upper bound,
// on how many items can be returned from the iterator. An integer field,
// _state, is incremented to keep track of this and to stop enumerating once
// we pass that limit. However, for Skip, there is no such limit and the
// iterator can contain an unlimited number of items (including past int.MaxValue).
// This test makes sure that, in Skip, _state is not incorrectly incremented,
// so that it does not overflow to a negative number and enumeration does not
// stop prematurely.
var iterator = new FastInfiniteEnumerator <int>().Skip(1).GetEnumerator();
iterator.MoveNext(); // Make sure the underlying enumerator has been initialized.
FieldInfo state = iterator.GetType().GetTypeInfo()
.GetField("_state", BindingFlags.Instance | BindingFlags.NonPublic);
// On platforms that do not have this change, the optimization may not be present
// and the iterator may not have a field named _state. In that case, nop.
if (state != null)
{
state.SetValue(iterator, int.MaxValue);
for (int i = 0; i < 10; i++)
{
Assert.True(iterator.MoveNext());
}
}
}
