public void DoesNotRequireEnumerationOfEitherInput()
{
IEnumerableWithCount<int> first = new ThrowingEnumerable(7);
IEnumerableWithCount<int> second = new ThrowingEnumerable(10);
IEnumerableWithCount<int> result = first.Concat(second);
Assert.AreEqual(17, result.Count);
}
public void FirstSequenceIsNotAccessedBeforeFirstUse()
{
var first = new ThrowingEnumerable();
var query = first.Concat(new[] { 1, 2, 3 });
using (var iterator = query.GetEnumerator())
{
Assert.Throws(typeof(InvalidOperationException), () => iterator.MoveNext());
}
}
public void FirstSequenceIsntAccessedBeforeFirstUse()
{
IEnumerableWithCount<int> first = new ThrowingEnumerable(0);
IEnumerableWithCount<int> second = new int[] { 5 }.AsEnumerableWithCount();
// No exception yet...
var query = first.Concat(second);
// Still no exception...
using (var iterator = query.GetEnumerator())
{
// Now it will go bang
Assert.Throws<InvalidOperationException>(() => iterator.MoveNext());
}
}
public void FirstSequenceIsntAccessedBeforeFirstUse()
{
IEnumerable <int> first = new ThrowingEnumerable();
IEnumerable <int> second = new int[] { 5 };
// No exception yet...
var query = first.Concat(second);
// Still no exception...
using (var iterator = query.GetEnumerator())
{
// Now it will go bang
Assert.Throws <InvalidOperationException>(() => iterator.MoveNext());
}
}