public void GetCheckType_ReturnsCorrectCheckType()
{
Assert.Equal(CheckType.E13B, AttributeHelpers.GetCheckType("E13B"));
Assert.Equal(CheckType.US, AttributeHelpers.GetCheckType("US"));
Assert.Equal(CheckType.Canada, AttributeHelpers.GetCheckType("CANADA"));
Assert.Equal(CheckType.CMC7, AttributeHelpers.GetCheckType("CMC7"));
Assert.Equal(CheckType.Unknown, AttributeHelpers.GetCheckType("UNKNOWN"));
Assert.Null(AttributeHelpers.GetCheckType(""));
Assert.Null(AttributeHelpers.GetCheckType(null));
Assert.Null(AttributeHelpers.GetCheckType("SOME_RANDOM_STRING"));
}