ATF-C(3)

atf-c(3) — C API to write ATF-based test programs ✨

okay bestie, welcome to the ATF C API manual — this is the atf-c library, fr fr. It's the C API to write ATF-based test programs. 💅

✨ NAME ✨

This page is about atf-c and this entire iconic squad: 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 ✨

bestie, here's the spellbook 🪄:

       #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, ...);

       void
       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 ✨

ATF gives you a C programming interface to implement test programs. C-based test programs follow this template:

             ... 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 🎀

okay so test cases have an identifier and they're made of three different parts: the header, the body, and an optional cleanup routine. All of these are described in atf-test-case(4). ✨

To define test cases you can use the ATF_TC(), ATF_TC_WITH_CLEANUP(), or ATF_TC_WITHOUT_HEAD() macros. Each one takes a single parameter that specifies the test case's name. ATF_TC() requires you to define a head and a body for the test case. ATF_TC_WITH_CLEANUP() requires a head, a body, and a cleanup. ATF_TC_WITHOUT_HEAD() requires only a body. 🫶

Important note bestie: these do not set the test case up for execution when the program is run. To actually do that, you need later registration with the ATF_TP_ADD_TC() macro, which is 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 gives you a way to easily define the test program's main() function. You should never define one on your own — 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. That name can be whatever you want, as long as it's a valid variable identifier. 🌸

After the macro, you're supposed to provide the body of a function. That function 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. It 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. These 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, you can also check for additional programs in the test case's body by using the atf_tc_require_prog() function. It 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, ...) — okay so this one is basically saying "bestie, this test case is gonna exit cleanly, trust." If exitcode is not -1, the runtime engine will validate that the actual exit code matches the one you passed in. But if it is -1, then the exact value gets ignored — periodt. ✨
• atf_tc_expect_fail(reason, ...) — any failure (fatal or non-fatal) that gets raised while you're in this mode is recorded. But here's the tea: those failures don't 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. 🫶 If no error is raised while running in this mode, then the test case is reported as ‘failed’. This mode is super useful to reproduce actual known bugs in tests. Whenever the developer fixes the bug later on, the test case will start reporting a failure, signaling the developer that the test case must be adjusted to the new conditions. In this situation, it's useful, for example, to set reason as the bug number for tracking purposes. 🐛
• atf_tc_expect_pass() — this is the normal mode of execution, bestie. In this mode, any failure is reported as such to the user and the test case is marked as ‘failed’. 💀
• atf_tc_expect_signal(signo, reason, ...) — expects the test case to terminate due to the reception of a signal. If signo is not -1, the runtime engine will validate that the signal that terminated the test case matches the one provided in this call. Otherwise, the exact value will be ignored. ⚡
• atf_tc_expect_timeout(reason, ...) — expects the test case to execute for longer than its timeout. ⏳

✨ Helper macros for common checks ✨

The library provides several macros that are very handy in multiple situations. These basically check some condition after executing a given statement or processing a given expression and, if the condition is not met, they report the test case as failed. 👑

The ‘REQUIRE’ variant of the macros immediately abort the test case as soon as an error condition is detected by calling the atf_tc_fail() function. Use this variant whenever it makes no sense to continue the execution of a test case when the checked condition is not met. The ‘CHECK’ variant, on the other hand, reports a failure as soon as it is encountered using the atf_tc_fail_nonfatal() function, but the execution of the test case continues as if nothing had happened. Use this variant whenever the checked condition is important as a result of the test case, but there are other conditions that can be subsequently checked on the same run without aborting. 🫶

Additionally, the ‘MSG’ variants take an extra set of parameters to explicitly specify the failure message. This failure message is formatted according to the printf(3) formatters. 💅

• ATF_CHECK(), ATF_CHECK_MSG(), ATF_REQUIRE(), ATF_REQUIRE_MSG() — take an expression and fail if the expression evaluates to false. ✅
• ATF_CHECK_EQ(), ATF_CHECK_EQ_MSG(), ATF_REQUIRE_EQ(), 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(), 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. 🔍
• ATF_CHECK_STREQ(), ATF_CHECK_STREQ_MSG(), ATF_REQUIRE_STREQ(), 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(), 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. 🔢 (Yes, ATF_REQUIRE_INTQ_MSG is written exactly like that in the source — no cap, we don't fix it. 💀)
• 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 🦋

The following functions are provided as part of the atf-c API to simplify the creation of a variety of tests. In particular, these are useful to write 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. This function exits the process in case of an error and does not properly mark the test case as failed. As a result, it should only be used in subprocesses of the test case; especially those spawned by atf_utils_fork(). 🚨
• 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 ✨

The following shows a complete test program with a single test case that validates the addition operator:

#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)

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Debian · February 23, 2021 · ATF-C(3) — that's the footer, bestie. Stay iconic and slay the day. 💅✨