better example on "testable expression" ?

["Durand, Jacques R." <JDurand@us.fujitsu.com>]

As the guideline starts to circulate,  here is a suggestion  for illustrating how the predicate could be worded, in a way that is more "testable" than the normative statement, also allowing the TA user (e.g. test suite writer) to not need be an expert in the spec domain:

 

Consider the following as a requirement from a specification on “widgets” :

• [requirement 100] “A widget MUST be of cuboid shape”.  (cuboid = like a cube but faces could be rectangular)

Here is a test assertion addressing this requirement:

 

TA id: widget-TA100-1

Target: widget

Normative Source: “widget specification”, requirement 100

Predicate: Each one of the [the widget] facets is of rectangular shape.

Prescription Level: mandatory

"The TA predicate is worded as an assertion, not as a requirement (the 'MUST' keyword is absent from the predicate but reflected in the prescription level). It has a clear Boolean value: either the statement is true, or it is false for a particular target. In the above case, it is only assumed that the testing environment has the ability to detect rectangular surfaces - e.g. by optical scan. The wording of the predicate takes this reality into account, instead of just repeating the normative statement - so this TA will provide guidance to a test suite writer who is not expert in 3D-geometry "

 

Jacques