public void Supply()
{
Nullable <int> n = 2;
Nullable <int> n0 = null;
Assert.Throws <ArgumentNullException>(() => NullableExtensions.Supply <int>(n, null));
Assert.True(n.Supply(() => 1).HasValue);
Assert.True(n0.Supply(() => 1).HasValue);
Assert.Equal(2, n.Supply(() => 1).Value);
Assert.Equal(1, n0.Supply(() => 1).Value);
// not called
Assert.True(n.Supply(() => throw new InvalidOperationException("Shpuld not be called")).HasValue);
}
