Public ReadOnly Property Current As TKey

public TKey Current {get;}

var sample = GetSample();
var test = CreateSample(sample);
int ix = 0;
foreach (var key in test.Keys)
    Assert.AreEqual(sample[ix++].Value, test[key]);

Dim sample As var = GetSample()
Dim test As var = CreateSample(sample)
Dim ix As Integer = 0
For Each key As var In test.Keys
    Assert.AreEqual(sample(System.Math.Max(System.Threading.Interlocked.Increment(ix),ix - 1)).Value, test(key))
Next