public void Grow()
{
ArrayPool <string> .Rent(out var array, 4);
array[0] = "1";
array[3] = "2";
var oldArray = array;
ArrayPool <string> .Grow(ref array);
Assert.IsNotNull(array);
Assert.AreEqual(8, array.Length);
Assert.AreEqual("1", array[0]);
Assert.AreEqual(null, array[1]);
Assert.AreEqual(null, array[2]);
Assert.AreEqual("2", array[3]);
ArrayPool <string> .Rent(out var newArray, 4);
Assert.AreEqual(oldArray, newArray);
Assert.AreEqual(null, newArray[0]);
Assert.AreEqual(null, newArray[1]);
Assert.AreEqual(null, newArray[2]);
Assert.AreEqual(null, newArray[3]);
}
