[Year 12 SofDev] Validation naming

[Guy Flaherty]

Hmm, interesting question Mark. Initially I would have said that I personally refer to an 'existence check' as one to make sure a value had been entered as well. Thinking about it though, and trying to imagine other possibilities, I am able to create situations where an 'existence check' would in fact test to see if the value entered is included in a list of values.

For example, you want a file to be loaded so you have a field for the filename to be entered. An existence check would make sure a name was entered, but could also be used to make sure that the file does indeed 'exist' in a directory.

In terms of Medicare 'numbers', I imagine they can only be valid with all digits and so may look like a range of numbers initially, however, if you think about this, it would likely be inefficient to design a system that could check for a valid medicare numbers based on range checks, as there are likely to be a large number of possible ranges, constantly changing and adjusting. Also, using range checks would impose on the organisation that any range must only include valid numbers, or else they would need to create new valid ranges each time a number in the middle of a range became unused. I can imagine that the most efficient manner to check to see if a medicare number exists is to do a check to see if it exists in a list of known values, which can be easily adjusted as old numbers are removed and new ones added.

I wouldn't normally explain existence checks in this manner, but I believe the exam's point is reasonable. Simply put, testing if something is null or not is simply using a list of one value to compare with, why can't you use a list of multiple possible values to determine existence?

Guy Flaherty
Xavier College
 
>>> Mark KELLY <kel at mckinnonsc.vic.edu.au> 14/12/10 11:59 AM >>> 
Hi campers.  A little audience participation question. Validation types in
the study design are:

   - existence checking
   - range checking
   - type checking

The 2010 SD exam <http:///postmortems/2010sd/SD2010exam.htm#c4> decided to
muddy the waters by describing these validation tests:

*Existence - to make sure that the number entered exists on Medicare's
database
Null - to make sure something has been entered
*
Now, I've always read "existence" as "has a value been entered?" (like
"Null" in the exam question).

How many of you good folk refer to existence testing as "existence in a
limited list", and how many would equate existence testing as null testing?

If you agree that the exam's terminology is unconventional, I am a bit
concerned about it being used in an exam where it could confuse students who
were taught the conventional interpretation.

Now I'm even doubtful about what the study design means by "existence
checking" - does it mean "null checking"?

Have a happy winding-down time, if you're luck enough to have one!

-- 
Mark Kelly
ICT Manager
Reporting Manager
IT Learning Area Manager

McKinnon Secondary College
McKinnon Rd McKinnon 3204
Victoria, Australia
Direct line / Voicemail: +613 8520 9085
Fax +613 9578 9253
kel at mckinnonsc.vic.edu.au

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