Re: [ubl-dev] Re: Test Assertions for UBL Calculation Model? Re: Re: [ubl-dev] Basic Invoice Exploration

[Stephen Green <stephengreenubl@gmail.com>]

Hi Ken

If I or anyone else from UBL TC or, via comments list, outside TC
write some test assertions, what should we do with them? Do we
hold back then from putting them on wiki? Should we start a UBL
document uploaded to Kavi UBL Documents page? I feel better
using the fuller expressiveness of a TA beyond just a single XPath
so I can use an XPath for not just predicate but target and
prerequisite too - lus more complex xpaths spread across several
variables then referenced in target or prerequisite or predicate. Still
it won't take too much to pull out from that the more simple xPaths
as proforma for the wiki. Just I want to capture all of the logic at the
same time as formulating the XPath proforma predicate so it leaves
no room for ambiguity. Plus I can 'kill two birds with one stone' by
getting to grips with TAs too and beta testing the markup a bit so
as to improve it as we go.

Stephen D Green



2009/6/24 G. Ken Holman <gkholman@cranesoftwrights.com>:
> At 2009-06-23 21:36 +0100, Stephen Green wrote:
>>
>> I added to wiki what could be a possible start on which entities
>> need the calculation assertions
>
> I have taken your examples and I've proposed a pro-forma use of the wiki to
> express the needed test assertions:
>
>  http://wiki.oasis-open.org/ubl/Example_Calculation_Models#proforma
>
> ... and fleshed it out with your first examples here:
>
>  http://wiki.oasis-open.org/ubl/Example_Calculation_Models/Invoice_Tax_Total
>
>> I realise it's a little different to your proposed way forward Ken.
>> I'm more inclined to think the way to go is to set up a project
>> for assertions about the calculation model which feeds directly
>> into the UBL TC and its process for authoritative approval
>> rather than start with a more distant model like the OIO-UBL one
>> which might be seen as a customisation model rather than
>> official UBL TC one.
>
> One ramification of using an assertion (with true/false results) is that the
> expression doesn't really look like a calculation, though of course it
> incorporates the calculation.
>
> Whereas I originally had:
>
>  sum( ../cac:TaxSubtotal/cbc:TaxAmount )
>
> ... to make that into an assertion it has to read:
>
>  . eq sum( ../cac:TaxSubtotal/cbc:TaxAmount )
>
> Now that isn't a big change, and I can live with it, but it changes the
> "feel" of the document.
>
> I can live with it because as a programmer, if I see the test condition I
> can infer what I have to do to make the test evaluate to true.
>
> And, it means that if someone has a TA engine they could run their generated
> instances through the TA engine and get a report that they've met the
> conditions.
>
> When it comes time to write the HISC document, we'll have to explain the
> perspective of the calculation model documentation as one of "confirming the
> calculation model has been followed" rather than "the steps of calculation".
>
> Jaymuz (and others) ... do you feel that test assertions can effectively
> document what you need to implement in your systems?
>
> Stephen ... can you improve on the pro-forma and examples based on your
> previous work with test assertions?  On the cover page I've assumed the
> expression language is XPath 2.0 and I've left the identification of the
> assertions to the step when we assemble them into our document.
>
> . . . . . . . . . . . Ken
>
> --
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