Use of FORMATLUHN

Products

• CA Test Data Manager (Data Finder / Grid Tools)

Issue/Introduction

As per the TDM documentation, FORMATLUHN function produces unique values as long as the original values are also unique. But while testing, there were same output for multiple input values. 

Original Value	FORMATLUHN Result	FORMATLUHN Result by ignoring first position
100000420	889123873	178912762
100000421	889123873	178912762
100000422	889123873	178912762
100000423	889123873	178912762
100000424	889123873	178912762
100000425	889123873	178912762
100000426	889123873	178912762
100000427	889123873	178912762
100000428	889123873	178912762
100000429	889123873	178912762

Environment

Release : TDM Portal 4.10

Cause

N/A

Resolution

The documentation is correct so here is: the last digit is a checksum digit, so from the 21 "unique" values only 3 are really unique (10000042, 10000043 and 10000044). 

The rest of the numbers are just the same numbers as one of those three with different (and invalid) checksum digit. 

That's why FORMATLUHN correctly output only 3 unique values - with the correct checksum digit in all cases. 

In other words the input values are not LUHN numbers and should get better results with FORMATENCRYPT and similar functions instead of FORMATLUHN function.