public void TestForEachLoopAndLinq()
{
var ports = new HashSet <string>(new[] { "New York", "Miami", "Los Angeles", "NewOrleans", "Jacksonville", "Houston" });
var trueEnumerable = new EnumerableCruise();
// For the real enumerable we can use Linq methods like Cast<T>():
Assert.All(trueEnumerable.Cast <object>(), c => Assert.Contains(c, ports));
var nonEnumerableExtended = new NonEnumerableCruise();
// For the class extended with GetEnumerator method we cannot use Linq methods:
//Assert.All(nonEnumerableExtended.Cast<object>(), c => Assert.Contains(c, ports));
// We can only use the instances of classes extended with GetEnumerator() in foreach loops:
foreach (UsPortsEnum port in nonEnumerableExtended)
{
Assert.Contains(port.ToString(), ports);
}
}
public EnumeratorLike(NonEnumerableCruise cruise)
{
this.cruise = cruise;
}
public static EnumeratorLike GetEnumerator(this NonEnumerableCruise cruise) => new EnumeratorLike(cruise);
