Tips for ABINIT users and developers

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====== Code Coverage ======

===== Motivations =====

In computer science, code coverage is a measure used to describe the degree to which the source code of a program is tested by a particular test suite. A program with high code coverage has been more thoroughly tested and has a lower chance of containing software bugs than a program with low code coverage. Many different metrics can be used to calculate code coverage; some of the most basic are the percent of program subroutines and the percent of program statements called during execution of the test suite.[ [[developers:coverage#cov|1]] ]

We aim that the test suite covers all the functionalities of ABINIT.

===== How does it work? =====


ABINIT is built with special options such that every function that is exercised (executed) in the program(s) is mapped back to the function points in the source code.

A .gcno file is generated when the source file is compiled with the GCC //-ftest-coverage// option. It contains information to reconstruct the basic block graphs and assign source line numbers to blocks.[ [[developers:coverage#cov|2]] ]

A .gcda file is generated when a program containing object files built with the GCC //-fprofile-arcs// option is executed. A separate .gcda file is created for each object file compiled with this option. It contains arc transition counts, and some summary information[ [[developers:coverage#cov|2]] ].

We use lcov to analyze the .gcda files for generating a html report  ([[http://ltp.sourceforge.net/coverage/lcov.php]])

===== How to trigger a coverage report ? =====

There is one slave dedicated to "on-demand" execution of branches by the developers, that produces a code coverage report, at present, higgs_gnu_7.5_cov. It can be launched by the general "[[https://bbportal.abinit.org|on-demand]]" interface (see [[bb:misc|Use of buildbot for ABINIT]], contact Jean-Michel or Xavier if you do not yet have access to it).
Code coverage reports from recent runs of the tests are available [[http://coverage.abinit.org/|here]]
If you see parts of the code which are not well tested, please contribute to improving coverage by writing new tests ! \\
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References \\
[ [[developers:coverage#cov|1]] ] [[http://en.wikipedia.org/wiki/Code_coverage]] \\
[ [[developers:coverage#gcov|2]] ] [[http://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/index.html#toc_Gcov]]