public void Test_valid_characters_is_empty() => TestHelper.AssertException <ArgumentException>(() => new CheckSum(new char[0], 10));
public void Test_length_is_zero() => TestHelper.AssertException <ArgumentException>(() => new CheckSum(new[] { 'A' }, 0));
public void Test_valid_characters_is_null() => TestHelper.AssertException <ArgumentNullException>(() => new CheckSum(null, 10));