An important aspect of tests is to know which parts of program is
used (covered) by the tests. An experimental analysis is
provided by the library library(test_cover).
We illustrate this here using CHAT, a natural language question and answer application by David H.D. Warren and Fernando C.N. Pereira.
1 ?- show_coverage(test_chat).
Chat Natural Language Question Answering Test
...
==================================================================
Coverage by File
==================================================================
File Clauses %Cov %Fail
==================================================================
/staff/jan/lib/prolog/chat/xgrun.pl 5 100.0 0.0
/staff/jan/lib/prolog/chat/newg.pl 186 89.2 18.3
/staff/jan/lib/prolog/chat/clotab.pl 28 89.3 0.0
/staff/jan/lib/prolog/chat/newdic.pl 275 35.6 0.0
/staff/jan/lib/prolog/chat/slots.pl 128 74.2 1.6
/staff/jan/lib/prolog/chat/scopes.pl 132 70.5 3.0
/staff/jan/lib/prolog/chat/templa.pl 67 55.2 1.5
/staff/jan/lib/prolog/chat/qplan.pl 106 75.5 0.9
/staff/jan/lib/prolog/chat/talkr.pl 60 20.0 1.7
/staff/jan/lib/prolog/chat/ndtabl.pl 42 59.5 0.0
/staff/jan/lib/prolog/chat/aggreg.pl 47 48.9 2.1
/staff/jan/lib/prolog/chat/world0.pl 131 71.8 1.5
/staff/jan/lib/prolog/chat/rivers.pl 41 100.0 0.0
/staff/jan/lib/prolog/chat/cities.pl 76 43.4 0.0
/staff/jan/lib/prolog/chat/countr.pl 156 100.0 0.0
/staff/jan/lib/prolog/chat/contai.pl 334 100.0 0.0
/staff/jan/lib/prolog/chat/border.pl 857 98.6 0.0
/staff/jan/lib/prolog/chat/chattop.pl 139 43.9 0.7
==================================================================
Using ?- show_coverage(run_tests)., this library
currently only shows some rough quality measure for test-suite. Later
versions should provide a report to the developer identifying which
clauses are covered, not covered and always failed.