libtap

News

  • Stig Brautaset will be giving a talk at YAPC::NA 2005 on Testing C programs with Perl. He tells me that libtap will feature heavily. Day 1, 3:55pm, in Grand Ballroom East according to the conference schedule.

Meta-information

Description

libtap is a C library designed to make it easier to write tests for your software. Tests written using libtap produce output that conforms with the Test Anything Protocol (TAP), first popularised by the Perl Test::* modules (in particular, Test::Harness and Test::Simple/Test::More).

Here's a trivial test program that demonstrates most of libtap's current features. 

#include <stdio.h>

#include "tap.h"

int
main(void)
{
    unsigned int root = 0;

    /*
     * Plan to run a total of 4 tests.  Running fewer or more than this
     * will generate an error.
     */
    plan_tests(4);

    /*
     * A simple example of a test.
     */
    ok(1 + 1 == 2, "Basic arithmetic works");

    /* The next test(s) need to be run as root.  Rather than doing something
     * like this at the start of the program:
     *
     *  int tests_that_need_root = 4;
     *  int total_tests          = 12;
     *
     *  if(getuid() == 0)
     *    plan_tests(total_tests);
     *  else
     *    plan_tests(total_tests - tests_that_need_root);
     *
     * you can tell the test system to skip over a certain number of 
     * tests.  All the code between skip_start() and skip_end() will
     * be ignored (including any non-test code).
     */
    skip_start(getuid() != 0,   /* Boolean expression      */
               2,               /* Number of tests to skip */
               "Skipping 2 tests because we're not root");

    /* Set a flag if we're running as root.  This code will not run
       if the boolean expression in the skip_start() call evaluated 
       to false */
    root = 1;

    ok(do_something_as_root(), "Doing something as root");
    ok(do_something_else_as_root(), "Did something else as root");

    skip_end;   /* Finished skipped tests */

    ok(ultimate_answer() == 42, "The answer's correct");

    /*
     * Produce a diagnostic message that indicates whether or not the
     * code was running as root
     */
    diag("We %s run as root", root ? "did" : "did not");

    return exit_status();     /* Return the correct exit code */
}

If this test program is run (and assuming that the functions ultimate_answer(), do_something_as_root(), and do_something_else_as_root() are defined and work as expected) then you will see the following output when run as a non-root user: 

1..4
ok 1 - Basic arithmetic works
ok 2 # skip Skipping 2 tests because we're not root
ok 3 # skip Skipping 2 tests because we're not root
ok 4 - The answer's correct
# We did not run as root

and the following output when run as the root user: 

1..4
ok 1 - Basic arithmetic works
ok 2 - Doing something as root
ok 3 - Did something else as root
ok 4 - The answer's correct
# We did run as root