ATF-C(3)

NAME 💖

hey bestie, welcome to ATF-C(3), Library Functions Manual — the C API that lets you write ATF-based test programs. no cap, this is the whole squad: atf-c, ATF_CHECK, ATF_CHECK_MSG, ATF_CHECK_EQ, ATF_CHECK_EQ_MSG, ATF_CHECK_MATCH, ATF_CHECK_MATCH_MSG, ATF_CHECK_STREQ, ATF_CHECK_STREQ_MSG, ATF_CHECK_INTEQ, ATF_CHECK_INTEQ_MSG, ATF_CHECK_ERRNO, ATF_REQUIRE, ATF_REQUIRE_MSG, ATF_REQUIRE_EQ, ATF_REQUIRE_EQ_MSG, ATF_REQUIRE_MATCH, ATF_REQUIRE_MATCH_MSG, ATF_REQUIRE_STREQ, ATF_REQUIRE_STREQ_MSG, ATF_REQUIRE_INTEQ, ATF_REQUIRE_INTEQ_MSG, ATF_REQUIRE_ERRNO, ATF_TC, ATF_TC_BODY, ATF_TC_BODY_NAME, ATF_TC_CLEANUP, ATF_TC_CLEANUP_NAME, ATF_TC_HEAD, ATF_TC_HEAD_NAME, ATF_TC_NAME, ATF_TC_WITH_CLEANUP, ATF_TC_WITHOUT_HEAD, ATF_TP_ADD_TC, ATF_TP_ADD_TCS, atf_tc_get_config_var, atf_tc_get_config_var_wd, atf_tc_get_config_var_as_bool, atf_tc_get_config_var_as_bool_wd, atf_tc_get_config_var_as_long, atf_tc_get_config_var_as_long_wd, atf_no_error, atf_tc_expect_death, atf_tc_expect_exit, atf_tc_expect_fail, atf_tc_expect_pass, atf_tc_expect_signal, atf_tc_expect_timeout, atf_tc_fail, atf_tc_fail_nonfatal, atf_tc_pass, atf_tc_skip, atf_utils_cat_file, atf_utils_compare_file, atf_utils_copy_file, atf_utils_create_file, atf_utils_file_exists, atf_utils_fork, atf_utils_free_charpp, atf_utils_grep_file, atf_utils_grep_string, atf_utils_readline, atf_utils_redirect, atf_utils_wait — C API to write ATF-based test programs.

---

✨ SYNOPSIS ✨

#include <atf-c.h>

ATF_CHECK(expression);

ATF_CHECK_MSG(expression, fail_msg_fmt, ...);

ATF_CHECK_EQ(expected_expression, actual_expression);

ATF_CHECK_EQ_MSG(expected_expression, actual_expression, fail_msg_fmt,
    ...);

ATF_CHECK_MATCH(regexp, string);

ATF_CHECK_MATCH_MSG(regexp, string, fail_msg_fmt, ...);

ATF_CHECK_STREQ(expected_string, actual_string);

ATF_CHECK_STREQ_MSG(expected_string, actual_string, fail_msg_fmt, ...);

ATF_CHECK_INTEQ(expected_int, actual_int);

ATF_CHECK_INTEQ_MSG(expected_int, actual_int, fail_msg_fmt, ...);

ATF_CHECK_ERRNO(expected_errno, bool_expression);

ATF_REQUIRE(expression);

ATF_REQUIRE_MSG(expression, fail_msg_fmt, ...);

ATF_REQUIRE_EQ(expected_expression, actual_expression);

ATF_REQUIRE_EQ_MSG(expected_expression, actual_expression, fail_msg_fmt,
    ...);

ATF_REQUIRE_MATCH(regexp, string);

ATF_REQUIRE_MATCH_MSG(regexp, string, fail_msg_fmt, ...);

ATF_REQUIRE_STREQ(expected_string, actual_string);

ATF_REQUIRE_STREQ_MSG(expected_string, actual_string, fail_msg_fmt,
    ...);

ATF_REQUIRE_INTEQ(expected_int, actual_int);

ATF_REQUIRE_INTEQ_MSG(expected_int, actual_int, fail_msg_fmt, ...);

ATF_REQUIRE_ERRNO(expected_errno, bool_expression);

ATF_TC(name);

ATF_TC_BODY(name, tc);

ATF_TC_BODY_NAME(name);

ATF_TC_CLEANUP(name, tc);

ATF_TC_CLEANUP_NAME(name);

ATF_TC_HEAD(name, tc);

ATF_TC_HEAD_NAME(name);

ATF_TC_NAME(name);

ATF_TC_WITH_CLEANUP(name);

ATF_TC_WITHOUT_HEAD(name);

ATF_TP_ADD_TC(tp_name, tc_name);

ATF_TP_ADD_TCS(tp_name);

atf_tc_get_config_var(tc, varname);

atf_tc_get_config_var_wd(tc, variable_name, default_value);

atf_tc_get_config_var_as_bool(tc, variable_name);

atf_tc_get_config_var_as_bool_wd(tc, variable_name, default_value);

atf_tc_get_config_var_as_long(tc, variable_name);

atf_tc_get_config_var_as_long_wd(tc, variable_name, default_value);

atf_no_error();

atf_tc_expect_death(reason, ...);

atf_tc_expect_exit(exitcode, reason, ...);

atf_tc_expect_fail(reason, ...);

atf_tc_expect_pass();

atf_tc_expect_signal(signo, reason, ...);

atf_tc_expect_timeout(reason, ...);

atf_tc_fail(reason);

atf_tc_fail_nonfatal(reason);

atf_tc_pass();

atf_tc_skip(reason);

void
atf_utils_cat_file(const char *file, const char *prefix);

bool
atf_utils_compare_file(const char *file, const char *contents);

void
atf_utils_copy_file(const char *source, const char *destination);

void
atf_utils_create_file(const char *file, const char *contents, ...);

bool
atf_utils_file_exists(const char *file);

pid_t
atf_utils_fork(void);

void
atf_utils_free_charpp(char **argv);

bool
atf_utils_grep_file(const char *regexp, const char *file, ...);

bool
atf_utils_grep_string(const char *regexp, const char *str, ...);

char *
atf_utils_readline(int fd);

void
atf_utils_redirect(const int fd, const char *file);

void
atf_utils_wait(const pid_t pid, const int expected_exit_status,
    const char *expected_stdout, const char *expected_stderr);

---

🌸 DESCRIPTION 🌸

okay so ATF gives you a C programming interface to implement test programs. C-based test programs follow this template, and yes bestie, you're gonna want to screenshot this:

... C-specific includes go here ...

#include <atf-c.h>

ATF_TC(tc1);
ATF_TC_HEAD(tc1, tc)
{
    ... first test case's header ...
}
ATF_TC_BODY(tc1, tc)
{
    ... first test case's body ...
}

ATF_TC_WITH_CLEANUP(tc2);
ATF_TC_HEAD(tc2, tc)
{
    ... second test case's header ...
}
ATF_TC_BODY(tc2, tc)
{
    ... second test case's body ...
}
ATF_TC_CLEANUP(tc2, tc)
{
    ... second test case's cleanup ...
}

ATF_TC_WITHOUT_HEAD(tc3);
ATF_TC_BODY(tc3, tc)
{
    ... third test case's body ...
}

... additional test cases ...

ATF_TP_ADD_TCS(tp)
{
    ATF_TP_ADD_TC(tcs, tc1);
    ATF_TP_ADD_TC(tcs, tc2);
    ATF_TP_ADD_TC(tcs, tc3);
    ... add additional test cases ...

    return atf_no_error();
}

---

🎀 Definition of test cases 🎀

Test cases have an identifier and are composed of three different parts: the header, the body and an optional cleanup routine, all of which are described in atf-test-case(4). To define test cases, one can use the ATF_TC(), ATF_TC_WITH_CLEANUP() or the ATF_TC_WITHOUT_HEAD() macros, which take a single parameter specifying the test case's name. ATF_TC(), requires to define a head and a body for the test case, ATF_TC_WITH_CLEANUP() requires to define a head, a body and a cleanup for the test case and ATF_TC_WITHOUT_HEAD() requires only a body for the test case. It is important to note that these do not set the test case up for execution when the program is run. In order to do so, a later registration is needed with the ATF_TP_ADD_TC() macro detailed in “Program initialization”.

Later on, one must define the three parts of the body by means of three functions. Their headers are given by the ATF_TC_HEAD(), ATF_TC_BODY() and ATF_TC_CLEANUP() macros, all of which take the test case name provided to the ATF_TC() ATF_TC_WITH_CLEANUP(), or ATF_TC_WITHOUT_HEAD() macros and the name of the variable that will hold a pointer to the test case data. Following each of these, a block of code is expected, surrounded by the opening and closing brackets.

---

🦋 Program initialization 🦋

The library provides a way to easily define the test program's main() function. You should never define one on your own, but rely on the library to do it for you. This is done by using the ATF_TP_ADD_TCS() macro, which is passed the name of the object that will hold the test cases, i.e., the test program instance. This name can be whatever you want as long as it is a valid variable identifier.

After the macro, you are supposed to provide the body of a function, which should only use the ATF_TP_ADD_TC() macro to register the test cases the test program will execute and return a success error code. The first parameter of this macro matches the name you provided in the former call. The success status can be returned using the atf_no_error() function.

---

💜 Header definitions 💜

The test case's header can define the meta-data by using the atf_tc_set_md_var() method, which takes three parameters: the first one points to the test case data, the second one specifies the meta-data variable to be set and the third one specifies its value. Both of them are strings.

---

🍓 Configuration variables 🍓

The test case has read-only access to the current configuration variables by means of the bool atf_tc_has_config_var(), const char * atf_tc_get_config_var(), const char * atf_tc_get_config_var_wd(), bool atf_tc_get_config_var_as_bool(), bool atf_tc_get_config_var_as_bool_wd(), long atf_tc_get_config_var_as_long(), and the long atf_tc_get_config_var_as_long_wd() functions, which can be called in any of the three parts of a test case.

The ‘_wd’ variants take a default value for the variable which is returned if the variable is not defined. The other functions without the ‘_wd’ suffix require the variable to be defined.

---

🧚 Access to the source directory 🧚

It is possible to get the path to the test case's source directory from any of its three components by querying the ‘srcdir’ configuration variable.

---

🔥 Requiring programs 🔥

Aside from the require.progs meta-data variable available in the header only, one can also check for additional programs in the test case's body by using the atf_tc_require_prog() function, which takes the base name or full path of a single binary. Relative paths are forbidden. If it is not found, the test case will be automatically skipped.

---

👑 Test case finalization 👑

The test case finalizes either when the body reaches its end, at which point the test is assumed to have passed, unless any non-fatal errors were raised using atf_tc_fail_nonfatal(), or at any explicit call to atf_tc_pass(), atf_tc_fail() or atf_tc_skip(). These three functions terminate the execution of the test case immediately. The cleanup routine will be processed afterwards in a completely automated way, regardless of the test case's termination reason.

atf_tc_pass() does not take any parameters. atf_tc_fail(), atf_tc_fail_nonfatal() and atf_tc_skip() take a format string and a variable list of parameters, which describe, in a user-friendly manner, why the test case failed or was skipped, respectively. It is very important to provide a clear error message in both cases so that the user can quickly know why the test did not pass.

---

🌈 Expectations 🌈

Everything explained in the previous section changes when the test case expectations are redefined by the programmer.

Each test case has an internal state called ‘expect’ that describes what the test case expectations are at any point in time. The value of this property can change during execution by any of:

• atf_tc_expect_death(reason, ...) — Expects the test case to exit prematurely regardless of the nature of the exit.
• atf_tc_expect_exit(exitcode, reason, ...) — bestie, this is you saying "okay this test is gonna exit cleanly, that's the whole point." If exitcode is not -1, the runtime engine pulls up and checks that the test case's actual exit code matches the one you passed in right here. If it is -1, then the exact value is just... not it, and gets ignored. 💅
• atf_tc_expect_fail(reason, ...) — the "we know, we KNOW" mode. Any failure, fatal or non-fatal, that shows up while you're in this mode gets recorded. But here's the twist: those failures do not report the test case as failed. Instead the test case finalizes cleanly and gets reported as an ‘expected failure’, and that report includes the reason you gave it. And if nothing goes wrong while you're in this mode? Then the test case is reported as ‘failed’. 🙈

This mode is literally made for reproducing actual known bugs in tests. So when the developer finally fixes the bug, the test case starts reporting a failure and is basically screaming "hey, adjust me to the new conditions." Which is why it's super useful to set reason to the bug number for tracking. Periodt.

• atf_tc_expect_pass() — the normal mode of execution, the default vibe. Any failure gets reported as such to the user and the test case is marked ‘failed’. No games.
• atf_tc_expect_signal(signo, reason, ...) — you're expecting the test case to terminate because it received a signal. If signo is not -1, the runtime engine validates that the signal that actually terminated the test case matches the one you provided here. Otherwise the exact value is ignored, bestie.
• atf_tc_expect_timeout(reason, ...) — expects the test case to execute for longer than its timeout. That's it, that's the whole expectation. ⏳

✨ Helper macros for common checks ✨

The library hands you several macros that are just so handy in so many situations. Basically they check some condition after executing a given statement or processing a given expression, and if that condition is not met, they report the test case as failed. Simple as.

The ‘REQUIRE’ variant of the macros immediately aborts the test case the second an error condition is detected, by calling the atf_tc_fail() function. Use this variant whenever it makes no sense to keep going with a test case when the checked condition isn't met. The ‘CHECK’ variant, on the other hand, reports a failure the moment it's encountered using the atf_tc_fail_nonfatal() function, but the execution of the test case keeps going as if nothing happened. Use this variant whenever the checked condition is important as a result of the test case, but there are other conditions you can still check on the same run without aborting. 💅

And bonus: the ‘MSG’ variants take an extra set of parameters so you can explicitly specify the failure message. That failure message gets formatted according to the printf(3) formatters. 🎀

• ATF_CHECK(), ATF_CHECK_MSG(), ATF_REQUIRE() and ATF_REQUIRE_MSG() — take an expression and fail if the expression evaluates to false.
• ATF_CHECK_EQ(), ATF_CHECK_EQ_MSG(), ATF_REQUIRE_EQ() and ATF_REQUIRE_EQ_MSG() — take two expressions and fail if the two evaluated values are not equal. The common style is to put the expected value in the first parameter and the observed value in the second parameter.
• ATF_CHECK_MATCH(), ATF_CHECK_MATCH_MSG(), ATF_REQUIRE_MATCH() and ATF_REQUIRE_MATCH_MSG() — take a regular expression and a string, and fail if the regular expression does not match the given string. Note that the regular expression is not anchored, so it will match anywhere in the string. iykyk.
• ATF_CHECK_STREQ(), ATF_CHECK_STREQ_MSG(), ATF_REQUIRE_STREQ() and ATF_REQUIRE_STREQ_MSG() — take two strings and fail if the two are not equal character by character. The common style is to put the expected string in the first parameter and the observed string in the second parameter.
• ATF_CHECK_INTEQ(), ATF_CHECK_INTEQ_MSG(), ATF_REQUIRE_INTEQ() and ATF_REQUIRE_INTQ_MSG() — take two integers and fail if the two are not equal. The common style is to put the expected integer in the first parameter and the observed integer in the second parameter.
• ATF_CHECK_ERRNO() and ATF_REQUIRE_ERRNO() — take, first, the error code that the check is expecting to find in the errno variable, and second, a boolean expression that, if it evaluates to true, means that a call failed and errno has to be checked against the first value.

---

🌈 Utility functions 🌈

These functions are all provided as part of the atf-c API to simplify the creation of a whole variety of tests. In particular, they're super useful for writing tests for command-line interfaces. 👑

• void atf_utils_cat_file(const char *file, const char *prefix)

Prints the contents of file to the standard output, prefixing every line with the string in prefix.

• bool atf_utils_compare_file(const char *file, const char *contents)

Returns true if the given file matches exactly the expected inlined contents.

• void atf_utils_copy_file(const char *source, const char *destination)

Copies the file source to destination. The permissions of the file are preserved during the code.

• void atf_utils_create_file(const char *file, const char *contents, ...)

Creates file with the text given in contents, which is a formatting string that uses the rest of the variable arguments.

• void atf_utils_file_exists(const char *file)

Checks if file exists.

• pid_t atf_utils_fork(void)

Forks a process and redirects the standard output and standard error of the child to files for later validation with atf_utils_wait(). Fails the test case if the fork fails, so this does not return an error.

• void atf_utils_free_charpp(char **argv)

Frees a dynamically-allocated array of dynamically-allocated strings.

• bool atf_utils_grep_file(const char *regexp, const char *file, ...)

Searches for the regexp, which is a formatting string representing the regular expression, in the file. The variable arguments are used to construct the regular expression.

• bool atf_utils_grep_string(const char *regexp, const char *str, ...)

Searches for the regexp, which is a formatting string representing the regular expression, in the literal string str. The variable arguments are used to construct the regular expression.

• char * atf_utils_readline(int fd)

Reads a line from the file descriptor fd. The line, if any, is returned as a dynamically-allocated buffer that must be released with free(3). If there was nothing to read, returns ‘NULL’.

• void atf_utils_redirect(const int fd, const char *file)

Redirects the given file descriptor fd to file.

🚨 Heads up bestie: this function exits the process in case of an error and does not properly mark the test case as failed. So it should only be used in subprocesses of the test case — especially those spawned by atf_utils_fork(). Don't be the main character who ignores this.

• void atf_utils_wait(const pid_t pid, const int expected_exit_status, const char *expected_stdout, const char *expected_stderr)

Waits and validates the result of a subprocess spawned with atf_utils_wait(). The validation involves checking that the subprocess exited cleanly and returned the code specified in expected_exit_status, and that its standard output and standard error match the strings given in expected_stdout and expected_stderr.

If any of the expected_stdout or expected_stderr strings are prefixed with ‘save:’, then they specify the name of the file into which to store the stdout or stderr of the subprocess, and no comparison is performed. 💾

---

🧚 ENVIRONMENT 🧚

The following variables are recognized by atf-c but should not be overridden other than for testing purposes:

• ATF_BUILD_CC — Path to the C compiler.
• ATF_BUILD_CFLAGS — C compiler flags.
• ATF_BUILD_CPP — Path to the C/C++ preprocessor.
• ATF_BUILD_CPPFLAGS — C/C++ preprocessor flags.
• ATF_BUILD_CXX — Path to the C++ compiler.
• ATF_BUILD_CXXFLAGS — C++ compiler flags.

---

🦋 EXAMPLES 🦋

Okay so here's a complete test program with a single... well, several test cases, and it validates the addition operator. Feast your eyes:

#include <atf-c.h>

ATF_TC(addition);
ATF_TC_HEAD(addition, tc)
{
    atf_tc_set_md_var(tc, "descr",
                      "Sample tests for the addition operator");
}
ATF_TC_BODY(addition, tc)
{
    ATF_CHECK_EQ(0, 0 + 0);
    ATF_CHECK_EQ(1, 0 + 1);
    ATF_CHECK_EQ(1, 1 + 0);

    ATF_CHECK_EQ(2, 1 + 1);

    ATF_CHECK_EQ(300, 100 + 200);
}

ATF_TC(string_formatting);
ATF_TC_HEAD(string_formatting, tc)
{
    atf_tc_set_md_var(tc, "descr",
                      "Sample tests for the snprintf");
}
ATF_TC_BODY(string_formatting, tc)
{
    char buf[1024];
    snprintf(buf, sizeof(buf), "a %s", "string");
    ATF_CHECK_STREQ_MSG("a string", buf, "%s is not working");
}

ATF_TC(open_failure);
ATF_TC_HEAD(open_failure, tc)
{
    atf_tc_set_md_var(tc, "descr",
                      "Sample tests for the open function");
}
ATF_TC_BODY(open_failure, tc)
{
    ATF_CHECK_ERRNO(ENOENT, open("non-existent", O_RDONLY) == -1);
}

ATF_TC(known_bug);
ATF_TC_HEAD(known_bug, tc)
{
    atf_tc_set_md_var(tc, "descr",
                      "Reproduces a known bug");
}
ATF_TC_BODY(known_bug, tc)
{
    atf_tc_expect_fail("See bug number foo/bar");
    ATF_CHECK_EQ(3, 1 + 1);
    atf_tc_expect_pass();
    ATF_CHECK_EQ(3, 1 + 2);
}

ATF_TP_ADD_TCS(tp)
{
    ATF_TP_ADD_TC(tp, addition);
    ATF_TP_ADD_TC(tp, string_formatting);
    ATF_TP_ADD_TC(tp, open_failure);
    ATF_TP_ADD_TC(tp, known_bug);

    return atf_no_error();
}

---

💖 SEE ALSO 💖

atf-test-program(1), atf-test-case(4)

---

And that's the whole page, bestie — you ate that. 🫶 This one shipped out of Debian with a date of December 16, 2024, and honestly? Iconic of them. Go write some tests. 💅✨