Re: [tag] Current issue with "TA for properties"

[Stephen Green <stephen.green@documentengineeringservices.com>]

Plus I made some further editorial changes to the section on
grouping using tags to make it fit with this prior section which
now introduces tags a little in advance.

I will upload this work as draft 1.0.4

Best

Steve

2009/5/21 Stephen Green <stephen.green@documentengineeringservices.com>:
> I've edited the section on property test assertions so that it now
> reads as follows:
>
>
>
> Test Assertions for Properties
>
> Requirements addressed by test assertions may be related to specific
> properties of a target. Assume there are specification requirements
> that define under which conditions a widget qualifies as
> “medium-size”. In other words, widgets do not come with a sticker that
> makes this categorization obvious by announcing small / medium /
> large. Instead, the size label is a property that is itself defined in
> the widget specification and that is subject to verification, like any
> other normative statement. In such a case, when writing test
> assertions, it is not a good idea to consider this property as part of
> the definition of the target category as in the case widget-TA101-1a
> and widget-TA101-1b, because the category of a widget could not be
> identified prior to doing any test on this widget.
> Assume that the following requirement defines the “medium-size” property:
> [requirement 104] “A widget that weighs between 100g and 300g and is
> from 5 to 15 centimeters long in its longer dimension, is a
> medium-size widget.”
>
> There is a major distinction between requirement 104 and requirement 101:
> requirement 101 uses “medium-size” as a prerequisite: its predicates
> only concern widgets that are already established as medium-size.
> requirement 104 defines how to qualify a test assertion as medium-sized.
>
> The test assertions for requirement 104 can be written as:
>
> TA id: widget-TA104-1
> Normative Source: specification requirement 104
> Target: widget
> Predicate: [the widget] weighs between 100g and 300g.
> Prescription Level: mandatory
> Tag:normative_property = medium-sized
>
> A tag, “normative_property = medium-sized” is assigned to convey that
> the test assertion evaluation relates to the property ("medium-size").
>
> TA id: widget-TA104-2
> Normative Source: specification requirement 104
> Target: widget
> Predicate: [the widget] is from 5 to 15 centimeters long in its longer
> dimension.
> Prescription Level: mandatory
> Tag:normative_property = medium-sized
>
> The test assertions widget-TA104-1 and widget-TA104-2 will be used to
> derive test cases that verify if the property "medium-size" applies to
> some widget. A "false" outcome for their predicates is an indicator
> that the medium-size property does not apply. It is not indicative of
> a violation of the specification itself. Such test assertions are
> called in this document "Property test assertions" to distinguish them
> from test assertions that are used as indicators of conformance to a
> specification. However, both types of test assertions are designed in
> the same way, with a predicate that indicates whether or not a target
> satisfies some feature or property.
> There is no mention of the “medium-size” property in the predicates of
> test assertions ‘widget-TA104-1’ and ‘widget-TA104-2’. This is because
> this property is precisely what needs to be established by a test
> suite containing test cases that are derived from these test
> assertions. Only when a target (here a widget) evaluates to “true” for
> these two test assertions, will it be considered medium-size. These
> test assertions are only concerned with the nature of these tests, not
> with how to interpret their outcome.
>
>
>
>
> 2009/5/21 Jacques R. Durand <JDurand@us.fujitsu.com>:
>> Stephen:
>>
>> I was indeed the one most in favor of doing this prefixing of the prescription level :-\
>> Realized that this does not work in general...
>> The tag appears to be the most flexible way: adding a new TA element might open a new can of worms.
>> I believe actually that it is good to not relate tightly the prescription level to the "intent" of the TA (here a property), which may change or may be more relevant to a combination of Tas.
>> Let us discuss this next week.
>>
>> Jacques
>>
>> -----Original Message-----
>> From: stephengreenubl@gmail.com [mailto:stephengreenubl@gmail.com] On Behalf Of Stephen Green
>> Sent: Wednesday, May 20, 2009 12:21 PM
>> To: TAG TC
>> Subject: Re: [tag] Current issue with "TA for properties"
>>
>> I've not been quite convinced that there was a clear case for putting the property definition in the prescription level. I'm still a little uncertain about merely using a tag but it seems better than overloading presription level so unless anyone objects I will include this in another draft (along with some very minor rewording Jacques has suggested offlist).
>>
>> Best
>>
>> Steve
>>
>> 2009/5/20 Jacques R. Durand <JDurand@us.fujitsu.com>:
>>> A medium technical issue with the current TAG draft:
>>>
>>> In section 3.3 "TA  for Properties":
>>>
>>> We recommend to mention the property ("medium-sized" ) in the
>>> Prescription
>>> element:
>>>
>>>
>>> Prescription Level: medium-sized:mandatory
>>>
>>>
>>> Because we want the prescription level to be associated with the
>>> definition of this property.
>>>
>>>
>>> [requirement 104] "A widget that weighs between 100g and 300g and is
>>> from 5 to 15 centimeters long in its longer dimension, is a medium-size widget."
>>>
>>>
>>>
>>> Suggestion: instead of this, use a tag for expressing the association
>>> of the TA to the property:
>>>
>>>
>>> Prescription Level: mandatory
>>>
>>> Tag: normative_property = medium-sized
>>>
>>>
>>> Rationale:
>>>
>>> - very close association between the Property and the Prescription
>>> level (as currently suggested) is a bad idea: it seems to suggest that
>>> the TA "widget-TA104-1" MUST evaluate to true (mandatory) for the
>>> property to be verified.
>>>
>>> But that does not work if  [requirement 104] has "or" instead of "and" :
>>>
>>> [requirement 104] "A widget that weighs between 100g and 300g OR is
>>> from 5 to 15 centimeters long in its longer dimension, is a medium-size widget."
>>>
>>> In that case we only want to indicate that the two TAs involved are
>>> related to the definition of this property, nothing more, as you could
>>> still satisfy the property even if you fail either TA. The
>>> Prescription level should only reflect the wording in the requirement,
>>> not be interpreted as a conformance statement.
>>>
>>>
>>>
>>> - a "normative property" should ultimately not be treated differently
>>> from a conformance profile. In both cases we don't want the
>>> Prescription level to be too closely associated with the profile or
>>> property (which may require a more complex combination of TAs, to be
>>> verified). Using a Tag is more appropriate for such a loose
>>> association, whcih has simply the value of an annotation (grouping) with no other formal semantics.
>>>
>>> - The TA could be associated with several properties.
>>>
>>>
>>>
>>> Jacques
>>
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