PRINTF STRINGS

In the descriptions that follow, for any function that takes as the last two parameters “char *, ...” it can be assumed that the char * is a printf() -like format string, and the optional arguments are values to be placed in that string.

TEST PLANS

int plan_tests(unsigned int)

 

int plan_no_plan(void)

 

int plan_skip_all(char *, ...)

 

You must first specify a test plan. This indicates how many tests you intend to run, and allows the test harness to notice if any tests were missed, or if the test program exited prematurely.

To do this, use plan_tests(), which always returns 0. The function will cause your program to exit prematurely if you specify 0 tests.

In some situations you may not know how many tests you will be running, or you are developing your test program, and do not want to update the plan_tests() parameter every time you make a change. For those situations use plan_no_plan(). It returns 0, and indicates to the test harness that an indeterminate number of tests will be run.

Both plan_tests() and plan_no_plan() will cause your test program to exit prematurely with a diagnostic message if they are called more than once.

If your test program detects at run time that some required functionality is missing (for example, it relies on a database connection which is not present, or a particular configuration option that has not been included in the running kernel) use plan_skip_all(), passing as parameters a string to display indicating the reason for skipping the tests.

SIMPLE TESTS

unsigned int ok(expression, char *, ...)

 

unsigned int ok1(expression)

 

unsigned int pass(char *, ...)

 

unsigned int fail(char *, ...)

 

Tests are implemented as expressions checked by calls to the ok() and ok1() macros. In both cases expression should evaluate to true if the test succeeded.

ok() allows you to specify a name, or comment, describing the test which will be included in the output. ok1() is for those times when the expression to be tested is self explanatory and does not need an associated comment. In those cases the test expression becomes the comment.

These four calls are equivalent:

int i = 5;

ok(i == 5, "i equals 5");      /* Overly verbose */
ok(i == 5, "i equals %d", i);  /* Just to demonstrate printf-like
                                  behaviour of the test name */
ok(i == 5, "i == 5");          /* Needless repetition */
ok1(i == 5);                   /* Just right */

It is good practice to ensure that the test name describes the meaning behind the test rather than what you are testing. Viz

ok(db != NULL, "db is not NULL");            /* Not bad, but */
ok(db != NULL, "Database conn. succeeded");  /* this is better */

ok() and ok1() return 1 if the expression evaluated to true, and 0 if it evaluated to false. This lets you chain calls from ok() to diag() to only produce diagnostic output if the test failed. For example, this code will include diagnostic information about why the database connection failed, but only if the test failed.

ok(db != NULL, "Database conn. succeeded") ||
    diag("Database error code: %d", dberrno);

You also have pass() and fail(). From the Test::More documentation:

Sometimes you just want to say that the tests have passed.
Usually the case is you've got some complicated condition
that is difficult to wedge into an ok().  In this case,
you can simply use pass() (to declare the test ok) or fail
(for not ok).

Use these very, very, very sparingly.

These are synonyms for ok(1, ...) and ok(0, ...).

SKIPPING TESTS

int skip(unsigned int, char *, ...)

 

skip_start(expression, unsigned int, char *, ...)

 

skip_end

 

Sets of tests can be skipped. Ordinarily you would do this because the test can't be run in this particular testing environment.

For example, suppose some tests should be run as root. If the test is not being run as root then the tests should be skipped. In this implementation, skipped tests are flagged as being ok, with a special message indicating that they were skipped. It is your responsibility to ensure that the number of tests skipped (the first parameter to skip()) is correct for the number of tests to skip.

One way of implementing this is with a “do { } while(0);” loop, or an “if() { } else { }” construct, to ensure that there are no additional side effects from the skipped tests.

if(getuid() != 0) {
        skip(1, "because test only works as root");
} else {
        ok(do_something_as_root() == 0, "Did something as root");
}

Two macros are provided to assist with this. The previous example could be re-written as follows.

skip_start(getuid() != 0, 1, "because test only works as root");

ok(do_something_as_root() == 0, "Did something as root");

skip_end;    /* It's a macro, no parentheses */

MARKING TESTS AS “TODO”

void todo_start(char *, ...)

 

void todo_end(void)

 

Sets of tests can be flagged as being “TODO”. These are tests that you expect to fail, probably because you haven't fixed a bug, or finished a new feature yet. These tests will still be run, but with additional output that indicates that they are expected to fail. Should a test start to succeed unexpectedly, tools like prove(1) will indicate this, and you can move the test out of the todo block. This is much more useful than simply commenting out (or “#ifdef 0 ... #endif”) the tests.

todo_start("dwim() not returning true yet");

ok(dwim(), "Did what the user wanted");

todo_end();

Should dwim() ever start succeeding you will know about it as soon as you run the tests. Note that unlike the skip_*() family, additional code between todo_start() and todo_end() is executed.

SKIP vs. TODO

From the Test::More documentation;

If it's something the user might not be able to do, use SKIP.
This includes optional modules that aren't installed, running
under an OS that doesn't have some feature (like fork() or
symlinks), or maybe you need an Internet connection and one
isn't available.

If it's something the programmer hasn't done yet, use TODO.
This is for any code you haven't written yet, or bugs you have
yet to fix, but want to put tests in your testing script
(always a good idea).

DIAGNOSTIC OUTPUT

unsigned int diag(char *, ...)

 

If your tests need to produce diagnostic output, use diag(). It ensures that the output will not be considered by the TAP test harness. diag() adds the necessary trailing “\n” for you.

diag("Expected return code 0, got return code %d", rcode);

diag() always returns 0.

EXIT STATUS

int exit_status(void)

 

For maximum compatability your test program should return a particular exit code. This is calculated by exit_status() so it is sufficient to always return from main() with either “return exit_status();” or “exit(exit_status());” as appropriate.