Testing, Interoperability and Technical Quality

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Writing Test Purposes (or TPs) is a critical early step in the development of a complete test specification. Each TP is a concise and unambiguous description of what is to be tested rather than how the testing is performed.

The TPs are based on the requirements identified in the relevant standard (or standards) from which the test specification is derived.

Generally, Test Purposes are written in prose (often with a loose structure and sometimes displayed in a tabular format). There is considerable benefit to be gained by having all TPs written in a similar and consistent way.

With this in mind, ETSI TC MTS has standardized a simple, structured notation called TPLAN for the expression of TPs (ES 202 553). TPLAN is defined with a minimal set of communications-oriented keywords but with the capability that permits users to define extensions to the notation which are specific to their application (technology) area.

TPLAN is suitable for expressing TPs for both conformance and interoperability tests. An example for interoperability is:

	TP id   : TP_COR_1100_01
	Summary : 'EUT reassembles a fragmented packet of an original length less
	          than 1500 octets'
	RQ ref  : RQ_001_1100
	Config  : CF_COR_23
	TD ref  : TD_COR_1100_01

	with { 'the MTU on the path from QE1 towards the EUT set at 1280 octets'}
	ensure that {
	    when { QE1 is requested to send data requiring a packet_length
	           of between 1288 octets and 1492 octets to the EUT }
	    then	{ EUT indicates receipt of the same data unchanged }

Benefits of using TPLan

  • consistency in test purpose, assertion and requirement descriptions- less room for misinterpretation; 
  • clear identification of pre-conditions, stimuli and responses; 
  • simplified migration from requirements to TPs or assertions; 
  • automatic syntax checking and syntax highlighting in text editors; 
  • a basis for a transfer format and representation in software tools.