8 library(test_cover): Clause coverage analysis

The purpose of this module is to find which part of the program has been used by a certain goal. Usage is defined in terms of clauses for which the head unification succeeded. For each clause we count how often it succeeded and how often it failed. In addition we track all call sites, creating goal-by-goal annotated clauses.

The result is represented as a list of clause-references. As the references to clauses of dynamic predicates cannot be guaranteed, these are omitted from the result.

Using show_coverage/2 with the option annotate(true), implied by ext(Ext) or dir(Dir), the analysis creates a line-by-line copy of the source files that is annotated with how many times this line was executed and with what logical results. These annotations rely on relating executable code to source locations which is shared by the source level debugger. Source level rewrites due to term or goal expansion may harm the results.

[semidet]show_coverage(:Goal)

[semidet]show_coverage(:Goal, +Options)

[semidet]show_coverage(:Goal, +Modules:list(atom))

Report on coverage by Goal. Goal is executed as in once/1. Options processed:

modules(+Modules)

Provide a detailed report on Modules. For backwards compatibility this is the same as providing a list of modules in the second argument.

annotate(+Bool)

Create an annotated file for the detailed results. This is implied if the ext or dir option are specified.

ext(+Ext)

Extension to use for the annotated file. Default is‘.cov`.

dir(+Dir)

Dump the annotations in the given directory. If not given, the annotated files are created in the same directory as the source file. Each clause that is related to a physical line in the file is annotated with one of:

###	Clause was never executed.
++N	Clause was entered N times and always succeeded
--N	Clause was entered N times and never succeeded
+N-M	Clause has succeeded N times and failed M times
+N*M	Clause was entered N times and succeeded M times

All call sites are annotated using the same conventions, except that --- is used to annotate subgoals that were never called.

line_numbers(Boolean)

If true (default), add line numbers to the annotated file.

color(Boolean)

Controls using ANSI escape sequences to color the output in the annotated source. Default is true.

For example, run a goal and create annotated files in a directory cov using:

?- show_coverage(mygoal, [dir(cov)]).

bug

Color annotations are created using ANSI escape sequences. On most systems these are displayed if the file is printed on the terminal. On most systems less may be used with the -r flag. Alternatively, programs such as ansi2html (Linux) may be used to convert the files to HTML. It would probably be better to integrate the output generation with library(pldoc/doc_htmlsrc).

[semidet,multifile]report_hook(+Succeeded, +Failed)

This hook is called after the data collection. It is passed a list of objects that have succeeded as well as a list of objects that have failed. The objects are one of

ClauseRef

The specified clause

call_site(ClauseRef, PC, PI)

A call was make in ClauseRef at the given program counter to the predicate indicated by PI.