System Under Test: FreeBSD

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UPD: The series of blog-posts “System Under Test” became a full-fledged project and has moved to its own domain. The most recent version of this article lives here now.

This article is part of series “System Under Test”. It provides an overview of the FreeBSD test suite and tools FreeBSD developers use to write and run tests.

What is the project about?

FreeBSD is a well known Unix-based operating system.


FreeBSD has one test suite. It contains ~3.6k tests and takes ~7.5 minutes to run on a virtual machine with 2Gb of RAM.

Getting Tests

The tests can be found in /usr/tests directory. Though, you may not have them there because of one of the following reasons:

  1. Test suite is not a part of any distribution prior to FreeBSD 10.0.
  2. Test suite is available out of the box only on FreeBSD 11.0 and newer.

If you are on FreeBSD 10.0 and want to see tests, then you just need to re-build the system from sources. Fortunately, it is very easy:

echo "WITH_TESTS=YES" >> /etc/src.conf
cd /usr/src
make buildworld
make installworld

Running tests

FreeBSD adopted approach used by NetBSD project. Within the approach they included the toolchain: Kyua and ATF.

Initially ATF provided both tools (e.g. test runner, report generator, etc.) and libraries (e.g. test cases, assertions, etc.). Over the years tools from ATF were replaced by Kyua.

To run tests you need to point kyua to a Kyuafile.

cd /usr/tests
kyua test -k ./Kyuafile

when it’s done you may request report:

kyua report

which shows brief information for all non-succeeded test and a summary, such as this one:

Test report


Kyuafile specifies which tests to run. It also can include other Kyuafiles. Here is an example:


When run kyua will execute all tests specified in lib/Kyuafile (and in Kyuafiles included from lib/Kyuafile), and then will execute three tests: ATF test some_atf_test, plain test some_plain_test, and TAP test some_tap_test.

Plain test is basically a simple program that returns non-zero if test failed and zero otherwise.

TAP tests are any possible tests, the only important thing there is an output. If test prints “ok whatever” then it succeeded, if it prints “not ok whatnot” - it has failed.

ATF tests intended to be more sophisticated. They may contain several test cases per file and provide useful information besides the exit code. Also, the tests may be written using C, C++ and shell.

Here is a part of an ATF test written in shell:


atf_test_case longname cleanup

longname_head() {
  atf_set "require.user" "root"
  atf_set "descr" "Test that usernames longer than 16 " \
    "characters are allowed (PR bin/39546)"

longname_body() {
  atf_check -s exit:0 -o ignore -e ignore -x "pw useradd $username"

longname_cleanup() {
  atf_check -s ignore -o ignore -e ignore -x "pw userdel $username"

atf_init_test_cases() {
  atf_add_test_case longname

If you try to find there a test written let’s say in C, then you will not succeed. All tests under /usr/tests are executables. The reason is that FreeBSD tools and libraries usually have their tests source code in their source tree. During installation these tests are compiled and copied to the /usr/tests. For example, if you want to see tests for libc’ stdio, then you need to look at /usr/src/lib/libc/tests/stdio. At the moment there is one test, here is part of it:

ATF_TC_BODY(test_append_binary_pos, tc)
  * For compatibility with other implementations (glibc), we set the
  * position to 0 when opening an automatically allocated binary stream
  * for appending.

  FILE *fp;

  fp = fmemopen(NULL, 16, "ab+");
  ATF_REQUIRE(ftell(fp) == 0L);

  * Make sure that a pre-allocated buffer behaves correctly.
  char buf[] = "Hello";
  fp = fmemopen(buf, sizeof(buf), "ab+");
  ATF_REQUIRE(ftell(fp) == strlen(buf));


FreeBSD has ~3.6k tests. The amount of tests is suspiciously small for such a big project. Since I was (and still am) afraid that I missed some important part I did ask on mailing list question about available tests, but didn’t get any answer so far.

FreeBSD has lots of various tools and libraries, but not all of them tested.

Maybe it’s a good starting point for a contribution?

Further reading

Drop me a line or ping me on twitter or Mastodon if you have questions!